With Micro-Maul I use some 40 quid (each) drills, because they give me the high quality I want,
And I do this step by step to mount them:
1. open the case and take the wires from the trigger
2. solder some longer, high current wires from the motor.
3. Take the torque changer off and reset the gearbox for direct drive (no torque limiter)
4. fold some custom straps from 2mm ali (one around the motor, and the other around the gearbox) Drill some mounting holes.
5. Get your chuck and give it a good bashing with your hammer (this works) then unscrew it clockwise. The chuck will come off.
6. Slide the wheel of choice onto the axle and check that its how far you want it to be (up or down). Now glue it in place with super-glue.
7. Get a 3-4mm drill bit and drill through the wheels axle flange and the axle it-self in one long drill. Find a 3-4mm bolt, slide through axle + wheel, then you have an attached wheel.
8. (you can then bolt your assembly onto the base using your straps).
I hope this is the info you need
Cheers, Ewan