Nicely done

I always collect the harpoons on my tank and then reset the encounter before handing them over to one or two other characters for the final push.

Once engaged, I park the 4 shammies near the harpoons and use mouse broadcasting to actually use the harpoons. It's still a pain in the ass, but I find it easier that way, and with a bit of luck you can fire off two or three harpoons on each click too.