Mist him heavily several times a day ... think rain, not just mist. Sometimes you have to mist several minutes before the drink instinct kicks in (especially if he is used to a water bowl)
It really is not a good idea, nor is it normal behavior for a cham to drink from a water bowl. If he does so, it's probably out of necessity and because he is NOT getting proper hydration from misting or a dripper.
Chams also have been known to defecate in water bowls, fountains, etc inside their cages. Obviously that can't be healthy.
If you're caring for him for the next 9-10 days, you may be able to convert him to drip-drinking if you are dilligent
Heck, give him a dripper AND regular good, heavy misting.
It sure would be better for the cham and then your friend might get a clue!
Good luck ... he's a nice looking cham.