Heres the circuit diagram without the relay.

If you have more then 2 wires for your controls, you will just need to add a resistor and diode for each additional wire and hook it up in a similar way. You will be limted to 4 wires since the joystick port only supports up to 4 axises.

Also, the diagram states a 500 ohm resistor, but this is not set in stone. You may have to use something other then a 500 ohm resistor to get the best voltage values, but probably anything from 10 ohm = 1k ohm will work at some level.