It's honestly very easy. There are quite a few videos on Youtube showing how to remove the sub/amp. I turned off the main screen, just do a quick Google search on how to power down a Tesla screen and that's all you need to do in my experience.
You don't have to do anything special with the wiring, it's just left/right and +/- given it's a dual voice coil. The Skar uses spring loaded connectors (I don't know the official name for this), simply stick in the factory connectors to the appropriate places (4 wires in total). The wires are different colors but generally +/- colors are pretty standard.
Here are a few haphazard photos I took: