Or just use the 'musicoverride=audiobank\Folder\Music.ogg/wav' Command in any script called during gameplay to change the music on the fly, say if a player gets near the kill limit it can change to a more tense aggressive beat to indicate to players they need to step it up.
You can set all this up before you build the game in the build set up and preview the changes as you go. Probably a much easier option for beginners than going straight to showing how to edit the setuplevel.fpi
From what I understand in the setuplevel.fpi certain things have to happen in certain states/order so messing with that even as a dev can be problematic unless you ABSOLUTELY know what your putting and where.
Other than that nice tut
smoke em if you got em