Just did this myself yesterday.
My old one was getting eaten up by rust different places, so decided to buy a brand new one at VW and have e paint. Also purchased new cable sets and the FM filter box since that also was very rusty.
anyway, first things first.. I made every thing ready, pulled wires and such before the swap (mostly cus it's to cold outside to work when I have no garage xD ).
I removed the c pillar trim to pull the wires through and get them connected the right way again when they new tailgate is fitted.
took about 2 hours installing new taillights, the tailgate and to put it all back together except the trim on the tailgate since I ordered a new one :)
Let me know if you get stuck and need some help, I'll try explain the best I can :)