Finally got around to installing the mirror from Mr. Messy - was a little difficult to get the 'ball' into the 'socket' on the back of the replacement mirror (literally, just the glass piece), but with it flat on a counter top over a dish towel, I forced it in without damage to the mirror. At that point it was just holding it in the receptacle and fixing the 2 screws to the bottom of the internal mirror holder.
2010 Honda VFR 1200F
2003 Aprilia Tuono