Well, if you want it for free roam, that's tricky since main.lua isn't fully decompiled yet (I THINK that's where the fight music is controlled anyways). Since just putting SoundSetHighIntensityStream (I forgot the exact wording, since it's been so long, and I can't be bothered looking it up now) will cause any fight to play the music you set.
But, if you just want it for a custom mission or so, then what you have to do is write in the lua script so that if PlayerGetWhoHitMeLast (or something like that) is part of this clique, then play this music, and if it's this clique, then play that music. Inconvenient, but that's the only method I can think of atm.