I don't have the controller for this game. I'm looking up info to see if it's feasible for me to make one from scratch using Arduino boards for prototyping.

Anyone know where I can get some info on what data is sent between a typical controller and the Xbox? Any info on the Steel Battalion controller specifically would be awesome.

Hi,
first off: wrong forum, Steel battalion is for the original Xbox.
2nd well, have fun if you are serious, I mean I could take a few pics of the inside (just have the middle part of one of mine opened for doing some mods anyways) so you would see that this definitely wouldn't be easy to do.