Quick post to show you guys how I added the motor to the leg.
I used a cell phone vibration motor that I picked up on ebay. covered the open space of the foot with styrene and just drilled a hole for the motor.
Used a piece of square tube to house the motor. Cut off the ball joint part of the leg and replaced it with the tube. After that, just added the connection parts for the armor.
All that was left was to drill holes throughout and leg to make room for the wires.
The final result: