www.shipyourreptiles.com has ALL the packing info and supplies you need. It is only legal to ship through SYR or Fedex itself (if you have already been approved). You cannot ship snakes through USPS or UPS at this time.
You will need overnight express shipping and a triple container; outer cardboard box, inner Styrofoam box, snake bag. You'll probably need a heat pack (40+hour). SYR has a video on all you need, packing snakes is easyI just sent out a few this week myself.