One Garmin motorcycle mount bracket - free with the Quest (2) if you shop around.
A piece of 3mm dural with a hexagon cut out to fit the fork cap.
A suitable fine pitch bolt to replace the dummy cycle valve bleed stud. A spacer and the original O ring from the stud. (so you still keep the oil in and water out)
A capping washer bigger than the hex cut-out (I used an old twin shock absorber top mount washer cos it fit and was shiney)
Adjustment is limited to moving the fork stachion around in the tripple clamp (top yoke) but a comfy spot was found to avoid hitting clocks and give the rider a good view. And the tilt angle is about right anyhow.
hope the link works, let me know if broken;
www.flickr.com/photos/chobbler/1550567056/