Alright, here goes:
1. Convert your sound file to .wav 44.1kHz 16-bit using Quicktime's Export feature. The duration can be up to 10 minutes. You must use a sound editor like Sound Studio to divide a piece into different sections, like 1 or 2 minute permutation segments. I forgot which is required, offhand, but take the time to experiment.
2. Save it to the data\sounds\music\<publisher>\<artist>\<title> directory in your Halo Custom Edition folder. Save each section as 0.wav, 1.wav, 2.wav, 3.wav, etc. Copy the path to this directory.
3. Open up cmd, which should be in your Halo CE folder and type: tool sounds <right-click to paste the path> ogg 1.0
4. Wait for it to finish processing the sounds; if you get an error, lower the quality by 0.1 until it works, or edit the sections or selection to use a shorter piece of music.
5. Open the .sound tag(s) and change their metadata in Guerilla to say "Music" rather than "Projectile Impact". This will fix your "overloading" problem in-game, as long as the music isn't extremely loud anyway. You can adjust the volume of each sound in the metadata also. Within the sound tag, you will have several permutations if you had different sections of the music, like 0.wav and 1.wav. If you had more than one permutation, then you need to change the index of each permutation to reference the following permutation, in order. Change "Total Permutation Count" to 1, and set the Next Permutation to 1, 2, 3, 4, etc., for however many permutations you have. The first permutation is 0, so "next permutation" set for the first permutation should say 1. In the last permutation, this should say -1 to indicate the end of the sequence of permutations. Finally, change the minimum and maximum distances to a very large number like 100000, so that the music is audible everywhere in the map.
6. Create a new sound_looping tag and place it in the same directory as your sound tag(s). Add references for each track and set each gain to 1.
7. Reference the sound_looping tag within a map file (either directly in the sbsp tag (scenario structure) or as an isolated reference within the References section of the scenario (scnr) tag) and build the map with tool. (Build-cache-file).
8. Open the map with Eschaton (mac) and recursively extract the lsnd tag you build into the map file. Import it into another map of your choice or save it externally as a tag to import later.
9. Reference your lsnd tag within the sbsp tag under Reference Swapper. If you have any additional changes, use Sparky's Plugins and the latest version of Eschaton to make those changes within the lsnd or snd! tags. Build-specific settings like "use xbox pcm blah blah" or "divide into multiple sections blah blah" are only available when running the sound tags through Tool.
Either you are groping for answers, or you are asking God and listening to Jesus.
