I know this ahs been mentioned before and wasn't working, but my friend who is a lv 51 hunter managed to get to hellfire penisula. How is that possible you might ask. Easy, warlock summon.
His location in our guidl roster said Hellfire Peninsula, but i haven't done it yet. Plz someone test and confirm.
Here's a SS of our guild roster:
He's at very bottom, he is now in Zangarmarsh and he's level 51