Ok I should have realized there is of course a way to have the motion rec as a mod source in the matrix. Simple motion record the ribbon and then use the ribbon as a mod source in the matrix.
I don't think this will allow different modulation per voice though, I think the ribbon can only have one value across all voices. (EDIT: Nope its polyphonic) And having free running motion REC/ability to disable retrig, and non synced to multiples of the recorded speed, like 1.3x speed would be great.