Oddly enough, there are many Trainers, but there is no given method with codes.
Freeman: Guerrilla Warfare: Cheat Codes Free Download
I think someone will come in handy.
In general, everything is simple here, there is a button on your Keyboard [End], it is usually located between the buttons [Delete] and [PageDown]
Push the button [End] and a kind of menu appears on the right of your screen (attached a screenshot)
There you select the function you need and click on it with the mouse.
This can be done both in the city and on the street, as well as during the battle..