Gamestop did not tell me about the token when I preordered my copy so I had to go back in and get the code.
It is a two step process. First you have to register the first code at gamestop's website (and then they will send you updates on new rewards) and that opens up the Elite website where you enter another code.
If it is done corrrectly you get a congrats page.
Plus you get a two-sided poster.
There is a time limit on the token. My receipt says June 30, 2012.