This mod is from Foobar2K:
This guide explains how you can mount a Gamecube memory card INSIDE your Wii, so that it does not need to be plugged in or visible from the outside. This was the next logical mod after my Internal Wavebird Receiver Mod and it now means both of my Gamecube flaps stay closed 99% of the time!
You will need:
Gamecube memory card
Some good thin wire
Electrical Tape or similar
Take apart your Gamecube memory card. Official cards have 2 or more triwing screws, but my 8mb unofficial one used 2 philips screws.
Once the screws are removed, carefully slide the plastic up to expose the memory card's circuit board, then remove the circuit board from the plastic moulding.
Cut 12 lengths of 5cm wire and strip 1mm from each end. I used multicore wire but most wire types will do as long as they are small enough.
Add a small amount of solder on to each of the large pads at the end of the memory cards. The solder should pool nicely on to each pad.
Solder a wire onto each of these pads. I personally found it best to tape the memory card board to the table to stop it from moving around while soldering.
Carefully take apart your Wii, all the way down to removing the motherboard from the base. Donít worry about removing the Bluetooth or wireless modules. You will need access to the underside of the motherboard you it is necessary to remove the heat sink. I used the following guide to make sure I took it apart correctly: http://www.informit.com/articles/art...?p=677908&rl=1
Now solder the other end of each of these wires to the corresponding point on the motherboard. Geepee thankfully already drew out a nice diagram for this, and I checked that it was correct using my multimeter.
BEWARE: This Diagram shows the pinouts from a top down view of the motherboard, obviously you will be soldering with the motherboard face down, so adjust as necessary. See my picture for a clearer idea.
I added a little extra solder to each pin to help my wires stick. Here's what mine looked like for reference:
Cover the back of the memory card with electrical tape, then place the memory card in the middle of the 4 heatsink screws (make sure it is in the middle so not to block the screws).
Tape the memory card in place with some more electrical tape. I also taped over my soldering on the board just to be safe.
Finally put your wii back together and test.
Tips + Troubleshooting
Check for solder bridges after soldering
Cover the soldered area with electrical tape to stop shorts
If you wish to use your external memory card on occasion then the simplest way to do this may be to add a switch between the +5v pin on the memory card and the motherboard. I have not personally tried this myself but I think it should work.