It's never really crossed my mind before, lol, but I'd think your best bet would probably be to pin it up as is if you want to display it stretched out. To keep it preserved you could put it in a air tight jar or a plastic sheet (like the one's for office stores).
I really have no idea though, might want to contact a natural history place or something.
Why would you want to do that? It is dead skin. It usually has poop or urates on it.
Sorry but thats just nasty.
but not always
get some stuff called MOD PODGE
(can be found at walmart or any craft store)
depending on how you are looking to display it is on how you would use the mod podge though.
get a few bad sheds (or peices) and test it out with those first in some various ways to see what way will work best for you and the way you want to display it.
I have thought about spray painting one with some red paint letting it dry then mounting it onto a peice of wood (1 x 4) painted black then once it's dried doing a little dry brushing with some gold leaf.
~sigh~ but I still have yet to get one in one peice cause they like to rip em in half
*** just from experiance
the mod podge gives them a plasticy feel but it will dry clear.
the more coats you put on it the stiffer it will get, but still use care working with them so not to tare it.
havent tried to put it on anything though***
I bet some polyurethane on a board would make it look pretty sick if you sliced it down the belly and laid it out to dry as flat as you can get it. Then just do layers and layers of the stuff to display it on the board