There are going to be five different kinds of Direhorns on the island-white,green,red,orange and blue. Below you can see a map with the locations of the different Direhorns on the island.
The important thing here is that you will need to get Ancient Tome of Dinomancy . This tome will allow you to tame Direhorns and without it you can do nothing. For now I don't know where you can get the Tome ,but it binds on a pick up so you won't be able to get it from the AH or other players.
For now the only known ability of the Direhorn pets is called Reflective Armor Plating. This ability will Deflects all spells cast in front of the Direhorn for 6 sec. It will be a channeling spell and it has 30 sec. cooldown.
Map with the locations of the Direhorns in the Isle of Giants
So this is the information that I have for the new pet for now. As soon as I find video with tamed Direhorns I will share it with you. I hope the post was useful. Keep hunting !