Hello, I made some more progress!First I wrote a basic M1000 emulator to ease further programming/hacking, see: http://gliglisynth.blogspot.fr/2014/08/matrix-1000-emulator.html

And second, I fixed NRPN support for the Matrix 1000, there was a silly bug that always added 128 to the "Param #". There's less than 128 parameters, so you could never edit anything!
Just write 0x00 instead of 0x80 and offset 0x4694 in the firmware and NRPN begins to work! (can be applied to 111 or 113)
Also, here's my modded version 124 with that fix: http://sfx.gligli.free.fr/zik/m1k/MATRIX_124.BIN

PS: voidtm, cool you want to port my code to the SixTrak! It won't be an easy task making it multitimbral tho.