Disconnect all wires and pipes etc inside your tailgate, what your left with is quite few wires that run off the loom, decreasing in numbers as it gets to the end,, with masking tape, tape the loose connectors to the loom itself, to stop them getting caught as you pull the wires through the tailgate., but before you pull the loom through, attach a peice of string or wire to the very end of the loom, this will help you when you come to rebuild the tailgate, as you pull the loom out, the string will follow, leave the string in the tailgate, but makeing sure it cant accidently come out! when you come to refit, simply reattach loom to the string, and gently pull through the other way.. simple!
Tom