1) Have a friend to invite you to a theater lobby!
2) Tell him to switch between player match and theater mode repeatedly
3) Do this until you get a black loading screen
4) It should show you that you're searching a player match, stay in there until the errors come up.
5) Press B twice when you see both errors, you should be in the Multiplayer menu now!
6) Go to Local and then Systemlink
7) Edit a class and hover over a random gold camo.
8) Tell your friend to back out and you should get the error saying that the game session is no longer available, you should be in player match now!
9) Switch the lobby to private match and create your classes (Remember to fix all your classes depending on your prestige)
10) Start up.
11) End the game and then go to a public match kill yourself then back out to make sure your classes stay
12) Enjoy your stuff