1. Unzip into your Battle for Middle Earth folder (where you installed the game)
2. Run the trainer (BFMETrainer.exe)
3. Run the game

When in the game:
Ctrl + Shift + 1: Freezes resources at 20,000
Ctrl + Shift + 2: Freezes population at 20 (so you can build as many troops as you want.
Ctrl + Shift + 3: Freezes power at 40 (get that Balrog you've always wanted)