[60041]

Proprietary towbars bought from a reputable manufacturer will be designed to fit the built in mounting points, and should not require any drilling or cutting of the car body; you will, however, most likely need to cut the bumper cover.
As for wiring, I would strongly recommend using a Volvo wiring kit, which simply plugs into the existing wiring harness and do not require any joining or splicing of wires. Modern wiring is so complex that modifying the harness in any way is not advisable.
You may also need to visit your dealer to have a software update.