Instructions
Start the "Star Wars: Battlefront II" game disc. Select "Galactic Conquest" or "Instant Action" mode for the most freedom in selecting which Jedi you wish to control. Note that you will have a more limited selection of Jedi if you choose the "Rise of the Empire" campaign mode.
Select "Rebel Alliance" or "The Republic" at the army selection screen.
Select any level you wish to play if you're in "Instant Action" mode. In "Galactic Conquest" mode you'll have to progress through a series of planets.
Select any troop class starting out.
Play the game with an emphasis on scoring high. Be extra careful to avoid death. Score as many kills, especially head shots, as possible and take over many enemy command posts.
Look for the notification at the bottom of the screen to know when you can play as a Jedi. For example, if you're playing as the Rebel Alliance on Hoth, it will say "Play as Luke Skywalker?" Press "Left" on the directional pad to select yes and you'll automatically spawn as the Jedi for that level.
Move around quickly and make as many kills as possible. Note the light saber bar at the bottom of the screen. It will deplete constantly and the only way to replenish it is to kill enemies. Once the bar runs out, you'll have to restart as a normal soldier.