Paul,
The controller that you were sent should control a 4th axis, you may only need a stepper or servo driver to use the facility, check on the deskcnc board to see if you have an "A: step and direction, if so all you will need is a device to drive you motor. Let me know and I will try to help you out.
"A Helicopter Hovers Above The Ground, Kind Of Like A Brick Doesn't"
Greetings From Down Under
Dave Drain
Akela Australia Pty. Ltd.
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)