I have some in my cupboard now. It is very effective for treating ill chameleons, and much easier to deal with than mixing up the adcham recipe. It was recommended to me by a prominent reptile vet as being a close second to Emeraid Critical Care, which is only available by prescription. I really think it is one of those emergency supplies that is worth just keeping on hand. Make sure that you get the Insectivore/Carnivore mixture. The other stuff is higher in sugar, which chameleons have a hard time processing.
A company called Lafeber makes Emeraid Critical Care for birds, and it is very effective as well. I had some for a long time, but my new puppy snagged the container recently and chewed it up. Expensive chew toy.
Yes, I have used it with chameleons. For long term use, you may want to force feed insects as well, or crunch up a few into the repta-aid just to make sure he is getting everything he needs.
A lot of times, vets give pretty generalized information for caring for reptiles. While it works well for the majority of reptiles, chameleons are a bit more sensitive. Pedialite would probably work better for you than Gatoraid. Have you seen the Adcham recipe for force feeding chameleons? I agree that cat food isn't a great thing to be force feeding for any length of time.