SDL Mixer supports MODs of several formats: .MOD, .S3M, .XM, and .IT. I realize you have to have a relatively new tracker for the Amiga to generate some of these but they work well. Likewise sdlBasic has been ported to AOS 4 and MOS so it should be easy to make new demos and programs to use these formats. (And a converter exists to export them to C++ in order to compile them.)
I don't know if the ProTracker event triggering mechanism is supported by the MikMod player in SDL_Mixer or not.