Perhaps I'm missing the big picture here but I don't see the way this can help with cooling of the cabin because selected alt on pressure controller (on ATR, at least) becomes relevant only when you start your descent. And I guess you don't want to wait till TOD to coll things down.
AFAIK only way to cool down the cabin faster is to increase airflow or reduce temperature of inflow. So if you fly ATR, temp controllers go to full cold and FLOW pb goes to HIGH. And be prepared for decreased performance. If you have problems with cooling of the cabin, check with maintenance if your packs haven't passed use-by date. Replacing the pack (or sometimes just cleansing the heat exchanger grille) can do wonders for air conditioning of the plane.
And just a little warning: If normal procedure can't be found anywhere in SOP, AFM or FCOM - don't do it, no matter how beneficial it might seem. You can always count on being surprised by the unforeseen consequences of improvisation.