Courtesy of AdamJosey - cheers dude!
This simple trick will allow you to operate the transtop and rear electric boot without having to worry if the rear window is up.
1. Disconnect battery...!!!
2. Remove rear storage bins and locate electronical plug to rear window under fuel filler pipe:
3. As you look at the plug with the push clip being at the top, the wire you need to earth is the solid red one. It is the wire on the bottom row... Second in from the left hand side with the push clip being at the top of the plug...!!!
Do not break the connection of the red wire just simple earth it to a good earthing point on the car body, or if you want to be flash, find the nearest wired earthing point.
Just use a pair of wire strippers and gentle remove a section of plastic sleave from the red wire and then connect a second earthing wire, i would suggest putting a spot of solder on the connection then wrap with electrical tape.
4. Reconnect battery!!!!!