Take a look at the fly I posted on the fly archive titled "red fly". This will also get used quite a bit in cold water. I have fished the petite series on the Salmon River when the fish were skittish.
That pumping is similair to the hangdown, Although he fishes with a single handed rod, Lani Wallers old videos are one of the best how tos on the wet fly swing. He definitely advocates the hang down and twitches the fly to try to entice a strike. he uses the line in his hand rather than pumping the rod, but it produces the same effect. I have heard and read guys letting there fly stay in the hang down for up to a minute to wait for the strike of a steelhead that may have followed in cold water.