They usually want you to not use clumping litter. You can fake the cat out and use dried beans in place of litter. Watch the cat and when he goes, you just take and put the feces in a small container, or even a plastic ziploc bag. Put the animal's name on the container/bag first, and stick the whole thing in the :censor::censor::censor::censor:, or run it to the vet.
They will do two tests on it, one is a smear and the other is a flotation. One is to find out if there is any internal problems and the other is to find out if there is a parasite invasion.