This creates a shortcut to open CoD4 with the mod whenever you enter "longtraining" in the terminal. You can replace the "longtraining" before the = sign with whatever you like if you want a different shortcut.
Press Escape and then Shift-zz
This saves the file.
Type "longtraining" into your Terminal, press Return, and enjoy.
Or whatever you set the shortcut as. You can use this whenever you want, even if you quit and restart Terminal.