XDD no joke i had that idea for fighting with music playing as well but dropped it because of this exact dilemma
well usually it is best done by lyrics BUT, if you plan to make money off of your comic DO NOT USE LYRICS FROM EXISTING SONGS, i was bummed to hear this since one of my characters is a big music fan, especially with the Beatles and those songs will cost you more than anything you can afford...
you could have a card before the scene that says "please turn on provided music" or something, thats the best i can think of