I agree with using the rollers and a video camera. It works extremely well if you have slow motion.

Has this cyclist changed their training load (ie hill repeats, distance etc), saddle position (fore/aft, up/down)?

Also with the cleats does the client have them turned to match their natural toe in/out? Cleats don't have to point straight forward as is a misconception.

Are they wearing their orthotics when riding? If so did they change their saddle height and fore/aft position to suit the added thickness of orthotic?

As for the medial rotaiton check for tibial torsion, tight medial Hamstrings, hip flexors or weak gluteals.

Also check saddle position. Some people put the nose of the saddle down. This will cause an anterior rotation of the pelvis and can exacerbate a medial knee position thru not activating gluteal muscles correctly.

good luck