Hey! I'm not an expert on this subject, but I might be able to get you a few steps closer to your goal.
First, if you don't already have it, download
GCncrypt. It'll help you convert AR code to RAW, and vice versa.
Make sure you read its documentation before using it.
Next, you'll need a workable copy of both the (US) and (JP) versions of the game.
I would recommend using
Dolphin to
create RAM dumps of both versions.
Here's a ROM of the US version:
http://romhustler.net/rom/gamecube/resident-evil-zero-uThis tutorial should help you understand where to proceed from there.
Good luck!