In Assault mode, play as the heroes. Go to Command Post 5 and play Chewbacca. You'll find Jabba's Sail Barge with the Command Post on top. Walk toward the front of it. You'll know it's the front because there is a Medical Droid and a Ammunition Droid. Stand right at the tip and face the ship. Take a couple steps back and jump at the ship, try to land on the tip of it. If all goes well, Chewbacca will get stuck and his health will drain. Right at the moment his health is gone, he'll begin to flip in circles really fast, and repeatedly drop various HAADs. If you have the Invincibility cheat code on, when you get stuck, press the pause button and click respawn.