1) An Official Nintendo Game Boy Micro Game Link Cable.
2) Any Gameboy Advance to Gamecube Link Cable. The directions below show how to use the following link cables:
- Official Nintendo Gamecube to Game Boy Advance Connector Cable
- Nyko CubeLink cable
- MadCatz SystemLink cable (For both GCN & GBA connectivity via the GBM)
3) Soldering skills
for the nyko cable go to step 3
Step 1: Official Nintendo Gamecube to Game Boy Advance Connector Cable Directions
Please note that I've only stripped the wires a tiny bit. You'll see why in the next step.