While searching on ways to create Programs with looping music, I have soon found that sound has its limitations in Alice. Being the generally nerdy, obsessive person I am, I spent the last couple of days experimenting on workarounds.
And here it is - A class that lets you easily Play, Loop, Stop, and Switch on the fly with background music.
The Zip archive contains: the class, a world with the class in action, and a short documentation with installation instructions.
Have fun!
Feel free to let me know if you use this in one of your projects, I'm eager to see how it goes.
Edit: So far there is a minor issue where lounger and/or higher quality songs pause at the end. I theorize that this is Alice loading the sound again. An easy way to fix this would be to compress the sound more, or chop the sound into individual segments, or both.