While playing a game press select, Up, Left, Down, Right, Up, Up, Down, Down, and Circle, Circle
While playing a game, press Select, Down, Down, Left, Right, Left, Right, Up, Up, and Square, Square
At the main menu,hold select and press Left, Right, Up, Down, Circle, Triangle, Square, and X
In deathmatch:lobby...Go upstairs and grab the rocket launcher, now go to the wall facing the lobby (youre still upstairs) start blowing up the wall and make a hole to the roof! where there is one of those BMF's at the top!
If you want to use mortars in multiplayer than follow these simple steps. First go to any level that has a sky (warlords is a good one). Next get a rocket launcher or fusion rocket launcher. Then go into a spot where you have clear view of the sky directly above you. Then aim up and fire. After a few seconds your rocket will run out of fuel and fall back down to the ground. This is good in Warlords to go on top of the fort and fire at the computer. It will take sometime to get used to aiming the mortars but its fun and cool.