Instructions
Run your installed trainer. The trainer has to begin running before "Command &Conquer: Zero Hour" if it is to work properly.
Run "Command &Conquer: Zero Hour." The game window will appear covering the box for the trainer application.
Press "Alt+Tab" to minimize the game window. "Command &Conquer: Zero Hour" will minimize and the trainer will appear.
Activate any cheats or changes you would like to make. Each trainer has a different method for activating cheats, so consult the "Read Me" text file that came with your program. However, most programs have a "Cheat" tab that has all the available cheats.