EA's put up an Army of Two site that lets you design your own Salem or Rios mask.
Once you've put your work of art together, you can check it out in 3D. Amazing.
As soon as Army of Two: The 40th Day ships on January 15, all you have to do is buy it et voila: your mask will be usable in-game.
Give it a waz. Check out our capture of demo play here.