Okay, so i am pretty sure this isn't an exploit so i'm going to post it here.
Basically, you can get reputation with the Huojin pandaren before MoP even hits, as the faction is already in the game.
While there is no direct way to gain reputation with this faction as of now, any quest that gives reputation for The Horde is going to give rep with huojin pandaren up until honored. (maxed friendly)
Of course this works just as well for the Tushui Pandaren via The alliance faction.
Just thought ill share this with those that might not have noticed/known/realised this
Here are the list of quests for Alliance:
http://www.wowhead.com/faction=469
And Horde:
http://www.wowhead.com/faction=67
Enjoy!