just let him bite you and ignore it, he'll get over it .....I would normally not say that, but if all you are doing is moving him for a few seconds, I don't think it will be much of an issue.
I used to be all careful too, esp when dealing with my snakes, but the little buggers can't really hurt you anyway; I've found its not worth the time effort to avoid it, just let them bite and ignore it. In most cases it wont even break skin
EDIT: As someone else mentioned, you have TRAINED him to be like that. Everytime you approach him, he puffs up being scared of you (he thinks you are some giant thing that will hurt him), and then when he puffs you (the giant creature) back off. Next time he sees you, he repeats this behavior because his objective is to get you away from him.
On the other hand, when he does this if you continue to slowly approach and even pick him up, he will *EVENTUALLY* be conditioned the other way. Your situation is likely made worse due to the conditioning that he has already undergone, but it is by no means irreversible. Simple reach in, let him puff up, and then GENTLY let him climb onto your fingers (I would put my hands slowly directly in front of him and maybe, if he allows, slowly move them under his chin). At that point he will probably climb onto your finger....but like I said since he has been negatively conditioned this might take several attempts and it is likely he will actually bite when you try to put your finger in front of him. If you are genuinely worried about the bite, just wear any old pair of gloves and you won't feel a thing...(honestly you won't really feel much without the glove anyway).
Whatever you do: DO NOT PICK HIM UP BY FORCE // FROM ABOVE as if you were "grabbing" an object. They HATE that and it will put an already defensive cham into a worse mental situation. You have to bring your hand in front of him and let HIM climb onto YOU. If you do this several times, he will eventually come to understand that although you are a "giant creature" you mean him no harm