For what it's worth, I've done both methods (sock in skimmer and in front of return), and I prefer the sock in front of a return; it dissolves a lot faster because there's more direct flow (vs my skimmer at least) and I don't worry as much about it damaging piping/pumps/filter/etc. When I did it in front of the return, the ~2 pounds was gone in about 24 hours without much squeezing, in the skimmer I was still squeezing a half-full sock several days later.
I take a scrap stick of wood, stick it out over the pool a foot or so with a brick holding down the other end, and tie a string to close the sock and to the stick.