Nice! an .ips patch would be welcome 
What are the differences between this version and the original?
Btw... would it be possible to do the opposite: play a modified neogeo rom as if it were the original xbox game? or add bosses or other hacks to the xbox version?
Anything is possible with enough patience and skill. This game has bosses, iirc.
Getting this game working on PC required -
1. Reverse engineering how the game loads Sprite data (it uses an index file, this logs whether or not the tile is flipped or not
as well as which blob of sprite data to use)
2. Reassembling the sprites based on this info
3. Re-scrambling the sprite data (on the xbox it is descrambled)
4. Re-scrambling the text data (on the xbox it is descrambled)
5. Reassembling the program data, it is split into 3 pieces
6. Hacking the palette data (in the third program rom) to be located in an empty space in the main rom space rather than
in an area that is normally reserved for ram (on real hardware)
Here are a couple of shots.
