If he can afford to have them professionally done he should think about a new pair

. You can probably get them repaired at the local dive shop since they deal in neopreme all the time.
I would do as RT has suggested and put some duct tape on the top and seal in a reversed vacuum tube to inflate. Then take some soapy water and wet the suspect area. The bubbles will give away the hole if it is a small one. Mark with crayon and apply shoe goo or a neopreme repair kit on the spot. If it is a large hole it can be sewn shut first with unwaxed dental floss before repair.
If you choose RT's method stay away from open flame

Tight Lines
------------------
Marty M
Steelheader.net