Sfassaert

I have an m5 that I'd like to control with a Roland es5. If I'm using the Leslie program on the m5 and I want to toggle between fast and slow I'd like to do that w a switch on the es5 but it seems I can only do that by assigning the speed control to the m5s exp pedal. If I knew the midi cc# that could be assigned to the speed then I could use one of the secondary switch functions on the es5 to do it and not use another memory slot. Is this possible?