Well, the real question appears to be, is he even dehydrated? Unless you're watching him 24/7, maybe you're missing him actually drinking. I don't mean that rudely, but it seems that a cham that is still eager to eat must be maintaining some level of hydration. In general, once animal becomes dehydrated his appetite will tail off rapidly. What & how often are you feeding him, perhaps he's deriving some/enough hydration from his meals? If possible, please post a picture of your cham, especially of his eye turrets, that is an easy clue to his hydration status. If you do believe you cham is dehydrated and deteriorating, please schedule a visit with your veterinarian, he/she can easily administer subcutaneous fluids which are much more easily absorbed by the body than fluids delivered forcibly into the GI tract (orally); a debilitated animal often has decreased GI absorbtion, not to menion the difficulting in administer liquid orally and the associated risk of aspiration into the lungs if done incorrectly. Above all, a veterinarian needs to be involved in diagnosing the cause of the dehydration and deterioration; i.e., cure the underlying cause of the dehydration instead of just treating the symptoms.