Here you can have a first look at the MIDI mapping for the Mega Drive / Genesis MIDI Mapping. Note that the interface works in two modes - a sequencer mode and a live mode.
The sequencer mode is meant for use with a host sequencer running on a computer, and lets the user control almost every facet and register of every voice independently via MIDI control messages.
The live mode has a polyphonic handler and assigns notes to any of the voices depending on which other voices are already busy. Parameter changes are written to all voices in the same way, so that they sound like one, polyphonic voice. This is suitable for live use with a keyboard.
The MIDI mapping in terms of which continuous controller number does what has not been completely finalised.