It looks very tricky...it involves editing the character model, soundsets, and a lot of others.
If you look, you might be able to find a modded version of the original 64 one, which you can play on teh comp with an emulator. ONe thing to watch out for is that one of the mods I saw also gave now-Rai a ridiculously game-breaking power hike. Appropriate, I know, but not so hot for fairness.