This is how I did mine -
I started by drilling down from the top of the ear, straight through to the other side. I chose a bit that was the same width of the starter holes for the Anovos-supplied parts.
For the hole with the switch, drilled again down from the top with a bit the same width as the threads on the switch. Next, I chose a drill bit wide enough that the kit switch could fit easily in the hole it would drill. I then started drilling
very carefully from the bottom until the hole was just deep enough that the threads protruded enough to screw the nut on the switch. At times, I was allowing the drill the turn only once between test fittings.
The switch went deep enough into the body of the ear that I had to cut a channel in between the holes so that the light could be inserted sufficiently deep into its hole. In the pic below, you can see where the Dremel cutting wheel got away from me - I'll have to fix that at some point
For the wire routing, I drilled a hole in the clear emitter tube and ran the plug down to the control board. Because the tube is so brittle, I covered the area I was going to drill with masking tape and started with a small bit. I worked my way up drill bit sizes until I had a hole just large enough for the plug.
Hope this helps.
Bottom view:
Top view: