Since the 22/45 has a polymer frame, which doesn't have removable grips, all you can do is add a slip on rubber sleeve. Hogue and Uncle Mikes make them. Most have finger grooves on them.
I have an Uncle Mike's in size large that is a smidge on the loose side on my 22/45. I'm going to get a medium and see if it will fit.
The down side to the rubber sleeve is that you'll have to remove it when you want to disassemble the gun, as it covers the takedown lever on the beck of the grip.
I have been told of a replacement part of the takedown lever and parts that will allow removal of the bolt by removing a screw on the top of the gun. I haven't got one yet, but I will soon.
[This message has been edited by DMSC (edited March 03, 2000).]