We recommend pouring the measured amount needed into an old sock. Then, either suspend the sock in front of a return or place the sock in a skimmer. Every time you pass, give the sock a squeeze and usually it is dissolved in a couple of hours.
Pouring it in a skimmer may allow it to get caught in a filter, and with a DE (or sand) filter there is the possibility that undissolved CYA will be back-flushed out of the pool. Hmmmm, wait a minute; their directions have the possibility of wasting the chemical, thus requiring the purchase of more.....
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.