I made up a bracket with a 'P' clip, some rubber and a bicycle handlebar mount from eBay. Seems to work OK for now, but I will be buying a Zumo 660!
Power is from a socket bought from Hein Gericke mounted in the fairing as per another post I saw on here.
http://picasaweb.google.com/lh/photo...eat=directlink
http://picasaweb.google.com/lh/photo...eat=directlink
http://picasaweb.google.com/lh/photo...eat=directlink
http://picasaweb.google.com/lh/photo...eat=directlink