Hi Steve,
There are a number of 'Hook' design lifting aids. I have seen several over the years and have a set in my garage. Usually it is a big aluminum hook that lays in the palm and is secured to the wrist with some kind of heavy duty velcro strap. I tried looking for them on line but no luck.
The only place I know that sells a version of this presently is Precision Training. These are the cult static (satanic?) contraction folks. They are also shameless hucksters. I really hesitate to send you over ther because this product is being hyped as the key to one ton shrugs, etc.
So hold your nose and put on some shades when reading this stuff. Do not give in to the snake charmers pitch.
All that aside, they do seem to have a high quality unit. They call them One Ton Lifting Hooks. They are much better than anything else I have seen. They are priced at $ 47, which is quite reasonable considering the quality. I paid $35 for mine and they are not as strong or good as these.
If you step dad has a palm, he should be able to position the hook on it. Then he could choose exercises, angles, benches, etc. to position himself so the bar does not fall out of the hook.
Not making any promises, but this may work for him.
Check out the hooks at
http://www.precisiontraining.com/hooks.cfm
HTH
Lee Michaels