If you have loaded a map at least once with this add-on installed, a settings.cfg file will be created into Left 4 Dead 2/left4dead2/ems/interneted_iatca

Here is the default code:
You may change the values for each key inside the table as you like.

• enableBots -> Allows bots to trigger car alarm when using fire ammo when set to true.

Don't change anything else inside the .cfg file or even putting words other than true and false, otherwise you would have to load a map with the add-on again to gain the default code or just copy the code above.

The addon has functionality on all gamemodes and maps, but for PvP gamemodes like Versus it is automatically disabled by Valve.

To make it work in Versus on your local server, right-click on Left 4 Dead 2 in your steam library, select Properties, click on the Installed Files tab, then click on the Browse... button.
Go to left4dead2/cfg/ and open addonconfig.cfg with a text editor or Notepad.

Finally, edit this line:
"versus" "1"