Reverse Wire Circuit?

[gaz j]

How do i locate and connect into the reverse wiring circuit to connect my parking sensors? i've drilled and fitted sensors but left wires in the right well of boot as i ran out of time. Any pics or advice much appreciated

 

[Scotty]

Can't you just tap the wire that goes to the reversing light bulb?

I dunno but that's what I'd be looking to do.