While I haven't done this, it seems like it would be relatively easy.
First I would get some velcro and fabric glue the first side to the cuff then do a simple stitch around the edge of it.
Second I would make a nice flap that could be attached to the cuff and put the other velcro side onto that (glue then simple stitch).
Lastly do a small cut on the cuff and slide the end of the flap into it and do a simple stitch along the cuff.
If this part makes any sense, then I feel accomplished, but when attaching the flap I would put it into the little cut in the cuff and pull up on both sides of the cuff (making a spine) and sew it that way then fold it over towards the other velcro and sew it again.