The basic steps to modify your SNES controller to connect to your computer via the parallel port.
Step 1: Strip SNES Controller Cable
Strip the end of the SNES (Super Nintendo Entertainment System) controller cable (the end that connects to the SNES), and tin the ends of the wires. If you don't want to cut up your controller you can just stick wires in the end that plugs into the SNES according to the diagram in step 3.
Alternatively (what I did), you could replace the SNES cable with one from something else, that way you don't need to chop up the controller. In my case I had a broken NES controller that I borrowed a cord from. It is also recommended that instead of cutting the cable you get a SNES controller extension cable and cut that up. In either case the steps are the same.