As far as I known it is done by a vet through a fecal exam or if you know someone who works at lab or something might be able to test the fecal sample. Other than that, I do not know of any at home test, but I may be am wrong. Anyone correct me, if I stand to be corrected please!
There is a very good book by Rodger Klingenberg called "Understanding Reptile Parasites". It explains every thing you would ever want to know about these nasty little creatures. Including how to test for and identify them. You would also need a microscope.
Unless you have a large collection of chameleons it would be best to take a fresh poop to your vet for a fecal twice a year. My vet charges $17.00 for a fecal at his office and he does them for $10.00 at some of the Repticon shows in FL. Some parasites are hard to recognize....for example pollen looks similar to coccidia and your sure wouldn't want to treat your cham for coccidia if it was just some pollen in the poop.
There you were, talking to me at the show in the SBCK booth yesterday and if you'd only mentioned parasites, I would have told you that I can do a "first pass" parasite test for you . You are welcome to stop by sometime here in M.B. with a fresh sample and we can do a fecal float and a smear to look for the "usual suspects."
Heading back to Pomona shortly for another full day of SBCK Booth Duty .