Installing rear view camera

[kiyakubuke]

Just received my rear view camera and want to try to connect it this weekend. Has anyone ever added an aftermarket rear view camera. I want to have the camera itself connected to a constant power source and run a connection from a 12v source activated by putting it in reverse to the head unit. On my Pathfinder I ran a wire all the way from the reverse lamp in the rear, but would like to avoid doing this now. anyone know where I can tie into the switch on the gear shift (6 speed)? also, any good connections in the boot (near the tags) to tie into a constant 12v? i.e.. power whenever the ignition is on?