Right now Inky is so overweight that he cannot bathe himself properly :(

I bought a bottle of Natural Chemistry's Waterless Bath today at the supply store because I thought maybe I could help him to keep clean.
Has anybody used this product?
The ingredients are: Water, natural enzymes, Aloe Vera, organic stabilizers.
It seems pretty safe and harmless to me. Opinions?

If it's a good idea, how often should I use it on him?
The directions say to spray it on, rub it in, then brush the cat. I use a furminator on Inky about once a week or so depending on how much he is shedding, should I just do it then?

If it's not a good idea, what else can I do to keep Inky clean?
We are working on helping him to lose weight right now, but he has far to go and I don't want to let his coat go until then.

Thanks in advance,
Lauren :)

Is he a long or short hair? I'd give him a once or twice a month bath in some quality shampoo (Pantane, Nexxus) or some of the quality pet shampoos (NOT anything Hartz puts out) - go to the Pet Catalogs for better products. If you bathe often, be sure to use a conditioner too so the coat doesn't get too dry.

He's a short coat.