I tapped into the 12v continuous inside the microphone housing just back from the mirror. The housing is easily removed either by hand or a plastic pry tool. There is a connector with 12v taped in place and not connected to anything. It's easy to fish a couple of wires from this location to where the mirror is. There are other posts that have good reference pictures of this 12v continuous source.
The first switch I bought had a plastic case surrounding the circuit board and it was 1" thick, but too thick to fit in the space above the microphone housing so I bought 2 very small switches consisting of a circuit board and 4 wires connecting to it (+ and -, in and out). I put insulation above it and electrical tape around the switch. Black wire from the 12v continuous feed to negative in on the switch, black and pink wire to the positive in on the switch. Positive and negative out from the switch to the dash cam.
Here is a picture of the switch and remote.
View attachment 303748
The location thing I mentioned was just a function of homelink - same concept as opening the garage door automatically when you pull up to your house. I have mine set to turn the camera off when I pull up to the mailbox about a hundred feet from the house before I even pull up to the garage.
By the way, I ended up using the other thicker switch with the case for the back dash cam. I went with Mobius 2 and replaced its internal battery with a super capacitor to hold up better with heat and long operating times. It's mounted at the top of the back glass and you can't see it at all when looking in the rear view mirror. Found 12v continuous in the back passenger side rear quarter. Works great - had it set up temporarily using the switched socket in the center console, but like it better hardwired and with the remote on and off capability.
