The Xbox 360 will only work with official licensed products, Microsoft signs all the hardware in some way. The exception to this is USB keyboards, but these will only work for entering text in the dashboard and stuff, you can't actually map keys from a keyboard in games.
Unless Ultimarc were to get licensed by Microsoft, which will never happen, the only way you'll be able to hook up a 360 to your cabinet will be via a joypad hack on an officially licensed joypad.