Just so you know, my vet told me (because im allergic to cats and I have 2) that for people who have allergy to cat saliva (not dander) there is a new way to make a cat non-allergenic. Theres a tranquilizer called Ace Promazine. If you use two drops of it in the cats food once a day, the drug can denature the cats salivary protiens and make them non-allergenic. I have the formulation but haven't tried it yet. It sounds like a long shot but its a new discovery...perhaps its worth a shot.
If he is allergic to the dander, it wont help though....