Mk6 Golf parking sensors power source

[sleep envy]

I'm going to retrofit a kit to the Golf, I've worked everything out except getting power to the control module.

The obvious point would be from the reverse light however that means running a cable from the boot lid, through the hinge grommet and back down through the boot space behind the panelling.

Is there any other way of splicing into the cable in the cabin without having to connect in the boot lid itself?

[sleep envy]

Genuine kit for an A3

Found the wire, it's on the N/S at the bottom on the C-pillar, black with blue trace.

Two spanner rating.