I used it on my 2006 GL1800. I put the unit and the car power adaptor in the right fairing pocket, and plugged the unit's Aux out to the Aux in that is in that fairing pocket.
I then routed the antenna out of the fairing pocket via a small channel I made in the pocket so the wire would not be pinched, and the cable was then routed under and along the lip of the saddle to the back and was placed on the rear speaker via double-sided Velcro. It worked great for years and many miles.
Hope this helps.