OOOH wait, Free! One way to add music that will loop to a map is to add it into the danger.py file (if the map has one, it will be found in the mission folder for the map). When you play the map, the music should play...It has worked for me. Keep in mind the music file must be one thats already a part of the game (or added into the Resources tab of the Editor by yourself)....Instructions for adding music to the .py file below.
Open your Editor and go to the resources tab to find the song you want (make sure you get the name correct)...If you have your game's music.ff extracted, then you can go to the musak folder to listen to them to make your choice (again, make sure you get the name correct).
Open the danger.py file with a Python editor (like Pythonwin) and type at the bottom, the example below (just replace the music_10sym1 with the music file you want to have play)...
Sound_PlayMusic('music_10sym1')
Adding music to the resources tab isn't too hard either. Place the song you want into your game's musak folder and then open the FFEditor, go to the Resources tab and scroll down to the music section (I guess you don't have to, but I like to). You can either copy and rename an existing track (you may not want to rename an in-game track or you may break the game...I think...It's safer to copy and rename) to the title of your new song (use lowercase letters) or you can click the New button (and then name the track, what you'd like).
Go up to the Source field and hit browse to find your new music in the game's musak folder (where you should have placed it). MAKE SURE TO SAVE YOUR WORK. Then you can add your custom track to your map's danger.py file.
I believe it was Gogglespizanno who told me about this set up, please forgive me if I got that wrong...Anyway, I hope that was clear enough and I hope it helps.
Dana