I know there are three difficulty setting, CASUAL, NORMAL or HARDCORE. I doubt that Dungeon Siege III for PS3 may have cheat codes.
I like to add more options for next patch for Dungeon Siege III for PS3 (Unless modding can be offered) below:
Add custom difficulty tab and "Use custom difficulty" checkbox
Adjust player damage modifier (10% to 800% in 10% step, default 100%)
Adjust enemy damage modifier (0% (Invincible) to 800% in 10% step, default 100%)
Adjust power sphere recovery rate (10% to 800% in 10% step, default 100%)
Contionous regeneration checkbox (20% of max health point every minute, default DISABLED)