Hello All! I found a way to make any class you want to before the required level.

*I do not take all credit to finding this...



Requirements

2 Controllers




Text Tutorial

[1] Turn on both controllers and go onto MW3




[2] Navigate to the Multiplayer Menu




[3] Sign Controller #2 into your Main Account




[4] On Controller #1, click System Link. A notice saying "You must sign in before you can play Online

or System Link matches." Don't do anything.




[5] Once the notice pops up, press A on both controllers and it should take you to the Xbox Live Menu

and make you sign in.




[6] Sign Controller #1 into your Main Account.




[7] Once you sign in, it will take you to the System Link Menu.




[8] Scroll down to Competition Mode and Disable it.




[9] Next go back up to create a class and make the class that you desire.




[10] Now hover over your classes and sign Controller #2 into a Silver/Offline Account




[11] Once it has signed in, press B until you get taken back to the Xbox Live Menu




[12] You should have the classes you made in the Create a Class.




[13] If it says your Create a Class is Locked, just click on it and it will instantly Unlock.