While rooting over the past week I found that I liked to use the rice sock on the outside of the head. I filled the sock with rice about halfway up and then tied a knot at the top of the sock so the rice could move around really well. After I heated the sock for 3 minutes with a cup with a little bit of water in it next to it, I draped the sock over the outside of the head like a strange hat. It worked great. Then I put a pillow on my lap, put the hot rice sock "pancake" on the pillow and rested the head on the side I wasn't working on on the sock, and worked on the warmed side. When that got too cool and hard, I turned the head over and rested it on the other side. I used the pillow because the rice got a bit too hot on my lap.
I just got so tired of trying to get that darn sock inside that little neck-hole.
Heat the rice in the sock and then put just the open end of the sock into neck and pour the rice into the head. Use a neck plug or stuff something int the neck hole. I like using it that way instead. It's much easier. No hair lost in the sock when you pull it out. When your done, put the sock over the neck and pour the rice back into the sock.