Instructions
Load up the game on the PSP.
Select "Campaign," then choose "New Campaign." Select any character with which you would like to play through campaign mode.
Work your way through the various campaign missions until you take control of the character, X2." You must select him before the mission starts to take control of him.
Press the "Triangle" button on your PSP. Your character will then switch your weapon to a light saber for you to use in the campaign.