I'm always impressed by the drive and skills of homebrew developers. But in this case, I ask myself...WHY?
For $25 I can pickup a XBOX (orig) and in a few minutes have it soft modded and mame or coinops installed. At that point, I'd put my $25 investment up against any x360 in a test of stability, speed, reliability, and ease of use. Not to mention the controllers are much cheaper and easier to hack.
Just my 2 cents.