To install mods for TimeSplitters 2, you will need a GameCube ISO of the game. Mod patches can be applied to these ISOs using a program called PhilePatcher, which can be downloaded from this link. If you need help with the program, I created a quick video guide on installing patches. Remember to have the Patcher create a duplicate of the ISO when patching it! This will allow you to apply other patches to it and create more modded ISOs without issue.