Trust me it int difficult. Yer need to access the rear of the fag
@Nig lighter socket. Use a meter to confirm which fag
@Nig socket wire is positive. With ignition oft cut through wires. Strip back and join them together with choc block. Strip back yer camera wires and connect to said choc block. Now pull oft A pillar plastic. Tuck cable out of sight under gear lever plastic surround, dash, then feed up A post. Either poke the cable above roof lining so it ends int middle by rear view mirror or undo sun visor and head lining screws to assist putting cable above it. It is easier to do this ont passenger side A post.
Second method is to get a carrier fuse and fit this to the fag
@Nig socket fuse int fuse box by yer passengers feet. It sort of piggy backs the eggsisting fuse. Now run cable up A post as above...