Editing music files at certain points of the game

[Aschwarz]

Hello, I was wondering if anyone knew how hard it would be to change music files for certain parts of the game?

With that being said would it also be possible to lock some of the music changes behind a difficulty?

 

A example of what I would want to do with this is add the soundtrack Two Steps From Hell - Protectors of the Earth

(the one used in the trailer for mass effect 3) To the part in ME3 where you have to hold off all of the elite enemies

before launching the missile at the reaper(right before the beam run) I would ideally want this soundtrack to only

be changed when playing on Hardcore or insanity difficulty.

 

For copyright reasons this would be a private mod.