At E3, the presentation of XCOM: Enemy Unknown
had Sid Meier doing a nice little cameo. Well, he's available as a squadmate as well as fellow game designer extraordinaire, Ken Levine.
As Kotaku shows
, just go into the squad configuration and change the names to the person you want to play as. That's it, simple as that. From the looks of it (and I don't have the game yet to try it out), the two seemed to be pretty decked out. Changing the names will turn off achievements, as it warns, so only play with them if you've finished the game or don't care about earning the achievements.
This begs the question, who else is hidden in the game as XCOM heroes?