BACKUP all files. Improper use could cause game to mess up.
First open the defaults.ini file in the main dir with notepad and change developer_mode = 0 to developer_mode = 1.
Then go to the /configs folder and add these lines to the default.ini file - under the cheat key section (down at the bottom):
Keyboard, V, CTRL, ALT
Keyboard, K, CTRL, ALT
Keyboard, J, CTRL, ALT
Keyboard, I, CTRL, ALT
Hit the corresponding 3 keys to activate that cheat.
You need to write these codes into keyboard_only in the configs folder also