Pixhawk 4 mini + ir pointer

Hello guys,
I am new to ArduPilot and Pixhawk.
I own a PixHawk4 Mini and I would like to mount an IR pointer on controlling it with a 2 position switch (RC8).
How ever I do not know:

  1. Where to mount it.

  2. How to set it up on Ardu Pilot.

I provide you with a diagram iot have an idea.
I have 5V on the MAIN OUT rail.
I have attached a tiny LED (do not know if needed).