Well, the mod I was creating was sort of a general audio mod. I was planning on adding more tracks to the game, along with the vanilla tracks. For Halo, Star wars, or Stargate, I'd have to replace the vanilla files themselves, plus mod entries into the files that tell the game what to play and what they're called.
Shouldn't there be some parameter for autocast? Here's what I was thinking.
Whenever a capital ship's shield reach a certain level, I think 50% or so, then a sound file plays to tell you that the shields are down. If someone were to isolate this command, perhaps we could use it to set when autocast should be used.