If you are using the pots from a 3 axis joystick, just keep them wired to the same connection points that they were wired to inside the joystick controller. It would just be a matter of adding/extending wires.
If you are substituting other pots, then you need to figure out which leads are equivalent to the ones that were in the joystick controller.
If you only have a 2 axis joystick controller, then you have a problem. Go back to the earlier recommendation in this thread.