Here's the start of the proof of concept page for X-Men Legends!
So, using the Dolphin emulator for GameCube, I've discovered that cutscenes in X-Men Legends are rendered in real-time, so they can be manipulated. I've used Dolphin's texture replacement feature to enhance the textures in some of the briefings. I'll post screenshots soon.
Right now, my plan is to get all the way through the game to unlock all the skins, and then I'll start playing around with the file structure more.
If anyone else wants to contribute to this thread, feel free! I recommend using Dolphin as it's the most stable emulator. (Also this is a reminder that we don't permit software piracy on this site)