There are some other tutorials about cheat codes on example: YouTube, but I want to make it as an solid tutorial.
First, you will need to type the cheat mode code. THE CHEAT MODE CODES ARE DIFFERENT, IT DEPENDS ON THE VERSION OF GAME.
Emergency 4 / 991 First Responders:
The cheat mode code will be magic.
Emergency 4 Deluxe
Cheat mode code will be fairz. If it doesn't work try fairy.
After that you can use cheat codes, here is the list:
CTRL+Shift+F7 - Automatically win the mission
CTRL+Shift+F8 - Automatically loose the mission
CTRL+Shift+F10 - Unlocks all medals and missions
CTRL+Shift+F11 - Gives 100,000 credits
If you are on laptop, you will need to ad Fn. Example: CTRL+Shift+Fn+F7. If it doesn't work, it means you must enable this in computer's BIOS. You can find more info about that on internet.
Note: Cheat codes are working on every version of the game.
If I need to change something or fix, please comment down below.
I Hope it helped you all.