Cheat Mode
Cheat mode can be used to edit the stats of your skirmish player. Use a text editor and edit the "[player name]skirmishstats.ini" file in the "c:\documentsandsettings\[username]\applicationdata\mybattleformiddleearthfiles" directory. The player's stats can then be edited to your heart's content.
Extra Resources
To receive a much-needed resources boost, pause the game and type "gold." Your resources will then increase by 700.
Extra Command Points
To receive 500,000 extra command points, type "the army" in the playing screen in either the good or evil campaign.
More Persona Points
The trick to increasing your persona points is to destroy as much as possible throughout a battle but leave one building standing at the end, and then save the game. Every time you load the game simply destroy the one remaining building and receive all the persona points.
Evil Darth Vader
This one only works in the evil campaign. On the playing screen, press CTRL+S+W and watch Darth Vader lead a battalion of Storm Troopers into battle. He is almost indestructible and wields a deadly light-sabre.