First, make sure the enclosure and temps/humidity are all spot on. Leave him alone for a week or so, then feed him an appropriately size meal. His aggressiveness may be coming from under-feeding. If he is still agressive after getting him on feed, then regular handling should calm him down some. If he is constantly striking whenever you try to get them out then you may need to use a hook or wear leather gloves until he gets used to you and realizes that you are not a threat. I glad you are taking him in instead of leaving him with his current owner...