Old thread but worth a bump!
JG knows what he is talking about! The snakes I purchased from him were packed excellently, not hot or cold on arrival and he was very adament that I contact him the moment they arrived.
If you follow these steps you should have no problems shipping herps. Just remember that if you use a heat pack, only use one that is designed for shipping live animals and that it does not come into direct contact with the animal. (NOT one of those hand warmers you get at walmart!) Most people will tape it to the inside top of the styrofoam with packing tape across its middle, or put it along the side of the box next to the animal, behind a bit of the packing/stuffing material. IE newspaper, pillow stuff etc.. Its also good to open it, shake to activate and let it sit out for about a 20 minutes before packing it in the box to be sure it activates and has plenty of oxygene to stay warm. It takes a little while for them to heat up.
If not done correctly these can over heat your animal. Proper placement is important.