I have two words for you: Super Soaker! I kid you not. If you can put a bit of eucalyptus oil in the mix, you're putting such a world of bad time on that kitty, he won't be back.
Most cats hate to get wet (all cats, if its not their idea) and I have yet to meet a cat that could stand the smell of eucalyptus, (thats what you smell in "Vicks")
Here Kitty, kitty, kitty!
Les