There are two ways to do MMT8 dumps - individual song or part dumps (via cassette tape dump outputs) or by full memory dump (by MIDI). MIDI dump won't do single song dumps. You'll have to use tape dump (just use a computer to record the data signal instead of a tape player).
Casio: FZ1, CZ101, PG380, VZ10M, SK8, SK60, RAP10, DP1 drums, DH100, CDP200, DM100
Yamaha: TX81z, TX802, SHS10, DTXv2
Roland: SH101, DR660, MS1, PM16, TR33
Others: Korg MicroKontrol, ES-1, Alesis MMT8, Emu ESi2000 & card reader, BCR2000, V-Machine