What are the biomechanical issues causing him to over pronate? Is he landing to externally rotated? Or is this actually a pelvic rotation that is causing this rather than a hip joint issue? If so this would be a internal rotation issue on the contralateral side and he would need releasing into internal hip rotation, stabilizing with the adductors and then the ability to hold this through mid to late stance, all on the contralateral side.

Please provide more info on the biomechanics.