Step 1: Get the Materials Needed
IPhone/iPod Computer Cord
Step 2: Open the NES Controller
On the back of the NES controller there are six screws that you have to remove. They are small and deep in the controller so you will need an extra small screwdriver.
Step 3: Modify the Circuit Board
In this step you will have to cut off some of the circuit board so that the end of the iPod cord can fit into the hole you will cut. In case you are wondering why you cannot just take the circuit board out completely, it is because if you don't leave it in the buttons won't be pressable.I cut off a good portion off the top where, like i noted in the materials picture, is where I'm gonna have the connector coming out. You will also have to cut the cord that goes from the circuit board into the NES.
Step 4: Cut the Hole for the IPod Connector
Using the Utility knife cut a hole for the iPod connector. This does take some time, but what I did is I started by making a slit then I just expanded it until the iPod connector fit though the gap.
Step 5: Finishing It Up and Screwing It Back Together
First stick the end connector into the hole you just made. If it's loose fitting than you might want to secure it with hot glue or epoxy putty. My hole was just big enough so it was nice and snug without anything to hold it in place. Next make sure you put the buttons back in correctly, and place the circuit board on. Screw everything back together and...Voila! You're finished!