To my knowledge you cannot. Im assuming your using an ISO like i am. Its just one more failsafe to make sure we dont pirate games online. But the game has the windows live program into it so the game wont let you play it without signing in. Well...it will...but you cant save..The only thing you can do really so search online for hours looking for a product key.
You CAN play AND save the game without all that GFWL crap. All you do is when you get the GFWL menu press CREATE ACCOUNT but then do NOT press continue. Scroll down and you will see create an offline account. Give it a name and let it sign you in. Now you can play the game and save using this offline account. The only thing you cant do is play online multiplayer or have all your in-game achievements recorded to compare with others.