I stumbled upon this program after beating NG the first time. I just used it to give myself the Plasma Sword MKII, the Dark Dragon Blade, and several Life and Ki upgrades before tackling the game again on Very Hard mode. I figured I'd play it kinda like Diablo--start over on a harder difficulty, but with a more bad-ass Ryu.
So far I'm liking it just as much as I did the first time I went through, if not more. This is the first xbox game I've picked up and played again immediately after finishing the first time. It's amazing.
Anyway, I found the program
here. A huge thanks to Pixel K for making it, and sharing it with us.
To use it, you gotta have the latest Evox dash, with TSR enabled. Then enter NG and load a game (or start a new one). From there, start up the program, connect to your box, and edit away! Just make sure that when you're adding items, you make sure the quantity is at least set to 1, and that the box is checked before clicking on "Write." Enjoy!