Thanks for your reply, Serapth.
The library itself has no dependencies. Only the sound generators do, as they are based on external audio/MIDI engines (including the well-known OpenAL and FMOD). Therefore, as long as those external engines are portable Modus is portable too.
At the moment I'm working on a sound generator for iOS based upon OpenAL, which will be included in the next release (v0.51), along with some examples. Unfortunately I can't tell you anything about Android, since I've never worked with it, but I have known that both OpenAL and FMOD can be used, so it should also be possible.