The Commodore parallel cable
You should follow these instructions if your drive has no parallel capabilities yet and you want to create a parallel port on your drive and then connect the cable to it. This is the more elegant method.
You need the following parts to build this cable:
Step 1. Take the long cable and solder one end of it onto the game plug.
Step 2. Solder the other end of the cable onto the user port plug. You should have the following connections:
You can find the description of all parts used on the diagrams at the legend page.
Source: The Joe Forster-STA homepage