Things You'll Need
Instructions
Click and remove the battery pack on your controller, then set aside. Unscrew the seven screws on the rear of the controller and set aside. Flip the controller face down and gently pry the controller's casing apart. Set the controller face aside (the section with the A,X,B,Y buttons).
Heat the soldering iron. In the meantime, choose the location on the controller face where you want your button to be installed (a common choice is slightly above the Blue button). Mark the spot with a black marker if needed. Drill a hole completely through the casing to accommodate the new button.
Dab a bit of adhesive gel to the head of the button switch, then press on the plastic button. Insert the button down through the hole you just drilled. Cut a small length of electrical wiring (a little less than two inches is recommended). Crimp the ends of the wire to expose fresh wire.
Wrap the small silver wires on the bottom of the button switch around the exposed wire. Solder the opposite end of the wire to the control plate in the small area between the black circles (where the thumb sticks rest) to the small, grayish dot. Allow to cool completely.
Reattach the two controller casings together and screw into place. Reattach the battery compartment and play a game, checking to see if your newly installed button works properly. If not, you may need to re-solder the wire.