I recall looking for this stuff in the MC-101/MC-707 manuals before, out of intellectual curiosity because I was kind of interested in doing something in 31-tone equal temperament or just intonation… then it dawned on me just how much work it would take to make that kind of music.
Anyway, I didn’t find anything as obvious as competing synths like the Hydrasynth, some of Korg’s synths, etc. have to offer in that area.
I found this vid featuring MC-707 playing microtuned piano - but I think he just microtuned the samples using software or some external device, then loaded the samples into the 707. Would you want to buy the 707 just to play samples… hmm…