As far as I just tested, it semi works if it finds the right offsets. I decompressed..some sort of enemy while using sniff.exe but it was only partial, not total. So it does work for Megaman X3 I believe.
Edit: Something that I think deserves a little posting. I've pretty much found how everything in the menu is drawn. Portraits, sprites, text, icons, life bars, 1 up, exit, chips, sub-tanks, etc..The only thing missing right now is the damn X-Buster icon. I can't find the X/Y coordinates of that. Once I find that, the entire menu is pretty much able to be redone, minus the boundaries. Still have to find those.