Just to finish off, I added the joystick and keyboard control code. The only problem is, there are limited built in keyboard shortcuts in Mach3, so I think I will have to add some of my own to the custom screenset I have designed.

All in all, I am pretty happy with this part of the project. However, I think I might design a PCB which will allow me to plug in the Teensy++ 2.0 module, and then solder all the connecting wires to the PCB, rather than solder direct to the actual module.