I'm pretty sure you press the Y button at some point to get the override to load, but I can't remember at what point you do. Any help would be appreciated. Thanks!

I have no clue what you're talking about my friend. When you upload the files onto your override directory, the game loads them automatically. Now if you're downloading files that require the "cheat console", then these mods will not be usable as the xbox doesn't have that kind of interface.

Try starting a new game!