What I've seen on mine is:
1. one side of the rubber grips may line up easier/better than the other side
2. I put the worst out of alignment/hard to fit grip on first, so I can reach through the frame with the fingers of the other hand to help push/pull/twist the hardest to install grip panel
3. you have to put the front down into the frame first, then set the back down on the frame and get it into the frame
4. it can take a lot of force (pushing forwards on the back edge of the grip panel) to get the holes lined up
5. have the screw in the grip before you start, but not protruding through the grip
6. start turning the screw easy and feel for any dragging that indicates cross threading
7. if it's smoothly turning then tighten it down snug, not too tight, the rubber will hold the grip screw in place as the rubber grips the screw threads pretty well
8. after the first side is done, install the other side
I almost never take the grips off, I mean almost never.
I suppose it might be pretty easy to open the screw hole up in a set of rubber grips but I've never tried it.