Don't think it still works, the ones you see now is because they have a controller plugged in and are using the gamepad control scheme (for the added aim assist )
this was the list that works with the older mw's
Code:A = //INVISIBLE JUST COPY THE BLANK SPACE (1 character) B = X = Y = < = > = LB = RB = DPAD LEFT = DPAD RIGHT = DPAD UP = DPAD DOWN = LEFT STICK = RIGHT STICK = LEFT TRIGGER = RIGHT TRIGGER =