Fitted mine a few days ago. Remove the left silver panel, you can get a stiff bit of wire (coathanger?) up from there to the front of the bike and attach the new Zumo power supply cable to that to pull it through, cable tie the wire practically all the way along the existing loom. Just behind the battery is the aux plug, I bared a bit of the outer on the positive feed to it and soldered a link for the fused supply, wrapped the solder joint in RTV tape for waterproofing. The earth simply goes onto the battery post with a crimped terminal. Silicon grease on all exposed terminals and the fuseholder.
Unit switches on and off with the ignition, loads better than the TT Rider I have been struggling with for the past year.
Hope this helps
Mike