Not sure, but I would imagine that if you go to Gamestop and get the digital download, the receipt would have the key and you should be able to use it register on the Early Access site (if it's still up). Haven't checked.
Go do it.....right meow.
Deadpool Xrage (Ultros)
Eriston Xrage (Ultros)
Siren - 75Bst/75Whm/75Rng (Retired June 2010)