I saw a tip in a helicopter flying book ( The Art and Science of Flying Helicopters, by Shawn Coyle ) where he suggests holding the cyclic with the ring, middle finger and thumb and using the little and index fingers to hold a pencil in place over the other two fingers.
Because of the pain caused, the stude learns to relax. I'm not sure how it would work in fixed-wing, because of the differences, but it might be worth a look.