One thing my mate had to do to satisfy the CAA was to demonstrate he could get in and out of the aeroplane unaided. To get in he would back his wheelchair to the trailing edge of the wing adjacent to the fuselage, and haul himself up to a sitting position on the wing. From here, he would lift the chair, fold it, and stow it in the aeroplane behind his seat. Then he'd haul himself onto the fuelage, lift his legs up and turn around to face forward, the lower himself into the cockpit manhandling his legs as he went.
He did this through sheer determination and developing tremendous upper body strength! I couldn't have done that. He got my respect!