He has to be level 58, there's the dark portal in the bottom right portion of the Blasted Lands
http://www.wowhead.com/?zone=4 . If he's not 58 and still wishes to go to outlands he can get a 70 mage to port him to shat. or get a warlock to summon him over. He has to have the burning crusade expansion pack in order to cross over.