To unock the Dr. Pepper bonus items, go to http://www.drpepper.com/promotions/ea/signin/, and register for an account. You can register three different accounts to redeem three different codes and get each bonus item. Enter one of the following redemption codes, and select the "No Purchase" option:
Choose the "Redeem" button to get a login for an EA account. Log in with your EA account information that is linked to Mass Effect 2. Select Mass Effect 2 from the game list, and select the desired bonus item. Repeat the steps with a new drpepper.com account to get the other bonus items.