This is barebones stripped template to show you exactly what you need to change to add mod support to any project. It sounds like it uses the best possible MOD processor. Very good quality, all effects supported (i believe). It’s also VERY VERY easy to use thanks to LiraNuna. Furthermore, it doesn’t affect arm9 performance AT ALL, arm7 completely handles it, besides saying Play, Stop, etc.
Grep for ModDemoAdded for the important (and sometimes out of the way) lines that were added.