Hey Caleb,
An MPG only needs 2 inputs and power so you could use one on a single C10 along with 4 motors.
If you want to have a manual axis selector switch like is used on
cnc4pc's pendant
you'll need another C10 to handle all the OEM trigger inputs (10 on mine).
You'll also have to get the Mach 3 Brain to process the signals.( cnc4pc gives one for 4 axis)
A switch is more convenient than jumping back and forth from the MPG and mouse.
An easier tool might be the
Shuttle Xpress or Shuttle Pro, I'm going to use one for my new build.
They've been on Ebay for $45.
Hoss