There are two small rectangular holes under the matt at the back the cubby hole.
Get some thin wire, something like bell wire about 2 foot long,feed this from the cubby to the passenger footwell.
Tape the sat nav end of the power cable to this fish wire and pull into cubby.
Then it's your choice wether to cut and tap into the ciggy lighter wires at the back of the dash or just use the lighter plug from the satnav in the socket.
I did the latter.