Most RC flight simulators read a chip (or something similar) installed either on the cable adapter or the handheld unit itself. I don't know of a way of bypassing that.

The question is: Why do you want to use a joystick to control an RC flight simulator? The point of the software is to help you with RC skills. Get Microsoft Flight Simulator X if you want to use a joystick.

If you want to use your radio, get the Transmitter Interface Edition. Otherwise you need the handheld unit to make the software work.

Rafael