Sorry I didnt get to you question sooner... Barbell Curls Lying Against An Incline basically laying on your stomach instead of the ever popular laying on one with your back.
Do you use a bar or rope for cable curls, maybe switch that up a little for a different sytle.
I love the drag curl, but dont think it would exactly isolate the precise area your asking about.
then there is always "He mans" aka "ear slappers" on the cables up. (Overhead Cable Curl)
Laying cable curl (which is just weird but different none the less.
Lying Close-Grip Bar Curl On High Pulley