A bedding of bran and/or oats
then provide (for hydration and some nutrients) pieces of
carrots
corn
squash
yam
apple
orange
which can just be placed on top of the bedding.
NOTE: Mealworms are NOT recommended as more than an occasional feeder for chameleons. Mealworms are somewhat hard for the chameleon to digest (exception: the very freshly molted/freshly shed mealworm that is still white is fairly soft and will digest more easily) and beside which they provide little/no nutrition to the chameleon.
Instead try superworm (aka Kingworms). These are easier to gutload properly, fairly easy to breed, grow bigger naturally, and are easier to digest.