I stopped at Radio Shack on the way home from work today and picked up both a 0-5k ohm and 0-10k ohm potentiometers.
I played with hooking up the 0-10k up to the Curtis controller. Works just fine like that. I saw on the box that the pots twist 300 degrees - too far to have turn from pressing the gas pedal- er, GO pedal.
By using the 0-10K pot, it only has to turn half as far. If you twist it TOO far, power to the motor does cut out. It reads anything above 5K ohms as an error and stops spinning the motor until you bring the resistance signal back down to 5K.
Here's the video.