From the starting menu where "New Game" or "Continue" can be selected (AKA main title screen):
Infinite Ammo:
U,R,D,L,U,R,D,L,L1,R1.
Invulnerability:
U,D,L,R,L,L,R,R,L1,L1,R1,R1,L2,R2.
Unlock All Levels:
At the new game/continue screen press Up, Down, Left, Right, L1, R1, L1, R1. This will unlock all levels in Instant Action Mode.
TIE:
Finish all 15 missions of main campaign and all 21 challenge missions.
X-Wing:
Finish all 15 missions of main campaign and all 21 challenge missions.
DORNIER DO-335 ARROW:
Beat all challenges and missions with all bonus and secondary objectives.
Big Heads In Cockpit:
At the new game/continue screen press Up, Right, Up, Left, Down, Right, Up, Left, Down, Right, ,L1, R1, L1, R1.
Get All Medals:
You have to beat all of the secondary objectives. The catch is you have to beat them on the first try.
How to unlock Star Wars X-Wings and TIE Fighter vehicles:
Use the Force in World War II. LucasArts unveiled the top secret news: that players of Secret Weapons Over Normandy will have the ability to unlock and pilot the Incom T-65 X-wing and Sienar Fleet Systems TIE Fighter vehicles from the classic Star Wars universe.
Upon completing the Secret Weapons Over Normandy 15-mission campaign and all 21 "Challenge" missions, skilled pilots will be rewarded with these two memorable starships that are available for use in the game's "Instant Action" mode. Console players will also be able to fly a squadron of X-wings head-to-head against their friend's TIE Fighters in split-screen multiplayer mode. In addition to the realistic look and authentic Star Wars sound effects direct from the Skywalker Sound library, players will also enjoy details such as watching the head of the X-wing's astromech droid track nearby targets. Can you be trusted with the most dangerous secrets from a galaxy far, far away? This is your finest hour!
