Ah, it works now, I found another version of MT32_CONTROL.ROM: there are two versions, the non patched MT32_CONTROL.1987-10-07.v1.07.ROM and the patched MT32_CONTROL.1988-09-30.vX.XX-patched.ROM. I was using the non patched version which makes hoot crash, now it works with the patched version.
Thanks for the answer.
The only thing which is missing is jump backward/forward in the music, too bad hoot doesn't do that...
But yes, MT-32 seems to have problems in hoot, Vampire Killer from Akumajo Dracula (MT-32 simulation version) has obvious bugs on my installation, someone recorded the track from MT-32 hardware and it sounds different
http://www.youtube.com/watch?v=60gIECQYfvo