I can't help you but your local JD Dealership should... just ask their Service/Parts Department and they will provide a print-out of the procedure & schematic for free. I know that my Dealership would do this, plus a mechanic would answer any questions I may have. Again, for free.
Here are two pics from the 4110/4115 service manual. Neutral switch is item R in first pic and item P in the second. Pics show location. I imagine the switch screws into the transmission, has a quick connection to attach it to the wiring harness. Good luck