How do I import my own background music to the game for a mod map. I've looked for tutorials but none of them seem to be what I want. So can someone either give me instructions about how to do this, or give me a link to a good tutorial on it.

Vyse did it. I think he said he munged in SWBF and then copied the munged .lvl file over and loaded it it in his LUA. You'd need to talk to him.