Could someone tell me how I can wire new speakers (which I build into the shelf on the rear of my mk4 5drs hb, behind the backseat), preferably from the radio to the back via the center console and through the middle of the car, underneath the handbrake unit all the way to the rear?

Or is there an easier way of hooking up my new speakers to the ones in the rear doors, without seeing the actual wires running through the car and without compromising water tight seals?

Any help much appreciated