Play as Drizzt.
At the main menu hold R1 and L1, then enter X and Triangle.
The Gauntlet Level
Defeat the game successfully under any difficulty level.
Defeat The Gauntlet level to unlock the Extreme difficulty setting.
Save the game, then drop the items you want to duplicate of your currenct character. Press Start and choose to change your character. Import your character from your previously saved game. The game will load up the character with the all the items in his inventory, then you can pick up the duplicated items that you previously dropped.
Resurrection in Multiplayer Mode
If a character dies during multiplayer mode, simply direct the remaining player to the previous save point. Walk through the light surrounding the save point. Doing so will revive your comrade with all of his items, but with half HP.
During gameplay hold L1 + R2 + Left + Triangle and press Start. A cheat menu will be unlocked.
During gameplay hold L1 + R2 + R3 + Left and press Start. Your fighter will be on level 20 and will be able to access all feats, and more.