Hi zeldaboy, robbio, trent or whatever your name is
Because you are asking so kindly - hmhm - here's an answer (this is ONLY for Singleplayer !!!):
A:
After activating a mod you might TRY one of your savegames. Sometimes it works and you can continue with your character. But the chance is quite low. Why ? Because if different equipment, cargo and so on is in your savegame the game WILL crash. You can improve the chance that a savegame still works when you sell EVERYTHING in old game and just try to transfer ship, engine and credits. But there is no guarantee.
B:
Note on a piece of paper your stats in the old savegame. Note everything (credits, weapons, equipment etc.). Quit FL. Save/Copy your savegames into new folder and delete then everything in your C:\My Games\MS\FL\accts\Singleplayer - Folder. Load Mod and start new game. Save and exit.
Now start
IONCross Freelancer Character Editor and edit this new character/save game with your stats. Save, load mod and enjoy.
But again: Only for SP. Editing character in MP on public servers is cheating.