OK, so I looked up the Nintendo 64 controllers->http://en.wikipedia.org/wiki/Nintendo_64_controller and according to wikipedia, they dont use a normal potentiometer. They use a light and light sensor to get the position of the switch.
I took apart an old controller, took out the joystick and the "potentiometer" controlling it, and wired to a dc motor. When its all the way down, no power. And as you twist it hits a hot spot in the middle then goes to about half power when all the way up (If that makes sense).
Also i checked out using the NES controller, is the any tutorial for a 64 controller?