To my knowledge:
The 8.2 pets work on a new system and set of functions exclusive to the 8.2 Game-Server, so completely recreating them on a non-8.2 server will prove problematic. I have recreated them within the confines of the 8.1 native pet-systems, but the point remains that you cannot completely replicate the 8.2 pets on a p-server as it stands.
If you wish to use the new pets, to say; create new pets. You would simply need to create the pet-card (item) > create the pet entry (summonresource) > link the card to the pet id > create pet skill tree's (the 8.2 system assigns random skills, this cannot be accomplished in 8.1 to my knowledge)
Each 8.2 pet is based off a pre-existing monster, meaning recreation is invariably easy. It will just take some creativity on your part as to filing out the new monsters base-stats and skill tree. Good luck.