The 605 uses the same grips as the 85, and there are plenty to choose from. I even have a set of the
Barami Hip Grips or them.
I have changed the grips around on my 85 a few times, and it couldn't be simpler:
1) Remove screw
2) Pull grip panels apart and remove from gun
3) Reverse the process with the new grips
As noted by Elvishead, the Hogues will go on differently. The alignment pin he spoke of is inside toward the bottom, and goes through a hole in the frame. Sounds like Elvishead's pin was in there tighter than mine, as the pin came out fairly easily for me. The new grips may or may not come with an alignment pin, so you may need to use the original piece in the new grips (the Hip Grip has a molded-in pin).
By the way, which grips are you looking at installing?