Start from here.Yallcenter.com,This guide covers how to disassemble your Wii. It is designed specifically for disassembling the Wii to install a modchip and shows you the absolute quickest and easiest method of disassembly to get to that point. It does not cover complete disassembly but it can serve as a good starting point if that is your intent.

Preparation

Deactivate WiiConnect24

Before you do anything you should deactivate WiiConnect24 it's impossible to disassemble the Wii without removing the battery and in doing so your console will have it's date and time settings reset, plugging the console back in after the reset can really screw up your WiiConnect24 channels like the Wii Shop, Wii News, and Wii Forecast.

This is done by selecting the system configuration option after clicking the "Wii" icon from the main Channel interface. Move to the right a few times until you reach the WiiConnect24 settings and deactivate it. Once that's done shut down the Wii completely and reboot it, check the setting again to make sure the change was fully accepted; the screen should look like the one below.

Backup Data

If you follow this guide you wont have anything to worry about but to be on the safe side you should backup all of your save games to an SD card if you have one. This is done by selecting the memory setting after clicking the "Wii" icon from the Channel interface. You'll have to copy the save games and other data one at a time to the SD card.

Remove Media and Accessories

Before you shut down your console you should remove any game discs that might still be in the console , push the eject button just to be sure. Once any discs are removed turn off the console and remove anything else attached to it. Remove any SD cards, Gamecube Memory Units, Wavebird wireless adapters, Power adapters, AV cables, the Wii sensor bar, etc.

Gather Tools

Once you've prepped your console for disassembly make sure you've got all the tools you need to actually disassemble your Wii. There are only two necessary tools but there are also a number of recommended tools.

Necessary Tools 

• #000 Phillips Screw Driver - A #000 is the proper sized Phillips screw driver for removing most of the screws from the Wii, a #00 can be used but it makes things a bit more difficult and unless you use some extra pressure on the smaller screws you risk stripping the head and ruining the screw. Despite the small size most hardware stores will carry precisions screw drivers that will get the job done.
• 3mm tri-wing screw driver - a 3mm tri-wing screw driver is pretty standard for Nintendo products it's been used on their consoles since the NES days. These drivers can be hard to find, if you can't find one at your local hardware store you may have to locate one online. Most modchip stores that carry Wii chips will also carry these drivers, or you could also find them for sale on eBay.

Recommended tools These tools are not vital to the disassembly but they'll make it much easier to do as well as hide any signs that you ever took it apart in the first place.

• Rubber Gloves - Your fingers are greasy and the Wii is Glossy and that's a bad combination. Even worse is getting an accidental electrostatic discharge to the Wii components, which could prove fatal. If you've got them I recommend wearing rubber gloves whenever you work on your console.
• Razorblade/Exacto Knife - this is recommended to help with the removal of the many stickers covering screws as well as the case feet. sliding the blade under the adhesive allows you to remove the sticky items without damaging them.
• Wax Paper - if you don't have any in the kitchen any waxpaper backing from a sticker sheet will do. I've heard many people suggest digging into their iPod box as most iPods came with an apple sticker. This paper is used to place the stickers and case feet on while you're working on your Wii, this way the adhesive stays fresh and doesn't get dust and other grime all over it ruining your chances of putting them back on.
• Container for screws - Whenever you disassemble something it's a good idea to have a container for screws, if you plan on doing this a lot you can usually find some nice containers at a crafts store or the crafts department of a department store. In a pinch I find that an empty ice cube tray works exceptionally well. Also, using a piece of corrugated cardboard with the ridges on it works well for organizing screws while you work.
• Magnet - Many of these screws are small and some are in recessed locations. A small magnet is useful for helping retrieve these screws from the console, If your drivers are magnetized that's even better.

Disassembly

Remove flaps covering Gamecube ports

Simply open up these flaps and pull them straight out. They should pop out without using much force.

Remove 3 Phillips screws from Gamecube Bezel

Use your #000 Phillips Screw Driver to remove these three screws.

Remove Gamecube Panel

Once the screws have been removed gently pull up on the black Gamecube Bezel disconnecting the clips along the bottom edge. Start at the left and work your way right. Once all of them have been removed you can slide the bezel out to the left removing it completely. 

Remove flaps covering Gamecube ports 

Remove Tri-wing Screws

Use your try wing screw driver to remove these two screws.

Flip over and Remove 1 sticker, 1 case foot and loosen one screw

Flip the console over onto the opposite side. Here you'll see for case feet and three small stickers that are covering screws as well as the battery door.

Use your xacto knife or razor blade to remove the lower right case foot and the upper sticker cover (the serial number should be upside-down) If you've got wax paper you should place them sticky side down on to the paper to keep the adhesive from getting dusty and losing it's effectiveness.

Also use your #000 Phillips to loosen the screw on the battery door. It will not come out it simply needs to be loosened. Once that's done you can pull the battery unit straight out without any effort.

Remove battery and 3 screws 

You should now see three more screws; Two Tri-wing screw and a Phillips. Remove them with the proper drivers.

Flip over and remove 2 case feet and 2 stickers

Flip your console again such that you're facing it's belly. You might want to consider placing a paper towel or other soft item between the console and the table to prevent scratching.

Here you'll want to remove two of the case feet from the back side and two screw covering stickers from the front side. Again use your xacto or razor blade and place them on wax paper if you've got it.

For this one I actually had an easier time simply using the nail of my thumb to pull up on the flat side of the case feet then I did with a blade.

Remove 4 screws

There should now be four tri-wing screws visible, remove them. The two screws at the back of the Wii, under the two rubber case feet are sometimes difficult to remove once unscrewed. They should come right off when you remove the case hood.

Slide off front panel and detach connector

The front panel of the Wii should just about fall off at this point. Keep the front panel from flopping about while you disconnect the LED connector by pulling it straight out.

Remove case hood

Gently separate the case lid from the rest of the console starting at the face.

Remove 4 DVD drive screws

You should now be able to see the DVD drive sitting atop the rest of the console. There are 4 rubber mounted Phillips screws here, remove these screws.

Remove 2 DVD drive cables

If you're not wearing vinyl gloves I recommend discharging yourself. This is best achieved by touching a ground connector on an electrical outlet. This is because after the next step you're going to be in contact with the Wii's components and an electrostatic discharge to a component could be potentially fatal to the Wii.

Once the screws have been removed the DVD drive can be gently separated from the rest of the console. Be careful, the drive shouldn't be flipped open more than 35 degrees as there are cables still attached to it.

With the DVD drive flipped up to about a 35 degree angle as shown in the previous picture, remove the white wire cable first by pulling it out flat with the circuit board.

You can now flip the DVD drive up to a 90 degree angle and remove the gray ribbon cable by flipping up the brown locking flap up and then sliding the cable out flat with the circuit board.

Sometimes the white wire cable pops out of it's black plastic hole, revealing a stump in the middle of the cable held together by a black cloth such as the one shown wrapped around the white white wire cable in the picture. If this were to happen, just shove this stump into the black plastic hole while reassemling the Wii as it can cause the DVD drive to not align properly.

Disassembly Complete

The underside of the DVD drive should give you a clear view of the modchip install area.

Re Assembly

Check modchip clearance

After you've fit your modchip ensure that it doesn't rub on anything and that the DVD drive fits in place as it did before without force it. Be sure to cover it with electrical tape to prevent it from shorting out as well.

Reverse the Steps

Once you're sure that your modchip does not interfere with anything simply reverse the steps outlined here, there is nothing special you'll need to do.

Set Date and Time

Once you've completed your reassembly you'll want to be sure to set the date and time on your console before you do anything else. The Date and Time were reset when the backup battery was pulled earlier and if you neglect to set it before running any games or applications you risk corrupting your save games or causing other software errors.

Re-Activate WiiConnect24

If you had to deactivate WiiConnect24 before disassembling the console you can safely reactivate it now that the date and time has been set.