Ok chaps,
Cheers for all the info. They are now fitted and I must say get very hot even on the lowest setting. I decided to trim the throttle slider with a hacksaw and a knife. It was a bit nerve racking but I managed in the end!!
I also had to use spacers to get the weights back on the bars without any sticking throttle
So now I have nice warm hands!!
I wired the grips directly to the battery as I'm not sure where the switched supply is. I think that should be fine as it takes a few seconds to turn the grips on and so shouldn't accidently happen!