Fly Any Ship in the Game:
(1) In your Game Directory, open the "Lucasarts" subdirectory
(2) Open the text file "SHIPLIST"
(3) Search for the text "Non flyable"
(4) Change that text to "Flyable"
(5) Save the file and start the game up. You may now fly any ship in the game.

Get Every Medal and Mission:
(1) Make a new pilot and name him "FongFong"
(2) Start the game
(3) Exit the game
(4) Go to the C:\Program Files\LucasArts\XWingAlliance\ directory
(5) Find and open the "FongFong0.plt" file.
(6) Delete it
(7) Start the game up one more time and everything should be unlocked.