Same question I had Rocky17. I know it is meant to go on the left grip, but I'm concerned it will take space where I normally like to rest my big, fat, thumb. I wear XXL gloves. In my post I asked for other potential locations and only got one other spot: Disassemble the PTT housing and install the switch in the RIGHT side switch housing, there is a flat on the housing that is supposed to have enough room in the hosuing for the switch and wiring. Haven't installed yet and I'm still not sure what I want to do.
Also, I'm trying to find a good accessable spot for the Kenwood FRS, my BMW RT buds have theirs in the left front pocket and I'm thinking the same for my ST1300A. Again, not sure yet.