Hi there,
there are 2 convertings tools available for download at
http://agisci.cjb.netWith mid2rol you can convert midi-files to rol-files. With rol2snd you can turn these rol-files into snd-files which are used by AGI. The only thing you have to keep in mind is that the notes in the midi-file must not be below a certain note (somewhere around A3).
There is no editor yet to create snd-files directly, but the converters work really well. Especially if you create midi-files yourself. With downloaded midis from the web, the converters will go fine with about 1 of 3 songs because these midi-files already contain many tracks. Chances are very high that a note too low is in the file.
I prefer playing melodies on one single track, because AGI cant use more than one track anyway

Let me know if you need further help.
b.o.k.