Put this code in as the "promo code"
5M9G1A
Put a legit email as the code is sent to you, and displayed. Once per IP. Just use some proxies and get some more. I got 3 one-months. Then sign up for a new xbox live account with that one month (ON THE XBOX, not website) and sign up for the MW2 Riot Shield and you get another 1 month added on