I used a bench grinder to smooth them out a bit after doing the major hacking with an exacto-knife. I didn't think about the freezer trick at the time. It was a temporary solution, and I didn't feel too bad about hacking up the OEM grips, since I was planning on replacing them anyway. I still have them around here, somewhere.
Yes, the Comp-I's do anyway. I don't have any other types of loaders to confirm, but I suspect HKS would work too... not my image: