Yeah she hasn't said how old he is. With a hatchling you can just let them hit your hand for a while until they figure out that biting doesn't make you go away. The same tactic with a 2000 gr breeder female... ouch...
Also OP I realize that while you really don't want him to make a mess on you, by putting him away whenever he threatens to do so you're rewarding that behavior. So, either hold him for very short periods and put him away before he gets to that point, or put on some old clothes and prepare to get stinky.