well you are asking to be told how to mod your game so you dont have to add a mod to your game
can you see where that gets confusing?
download my upgraded deck gun mods and look at the files in them. that will show you the files that are involved and then you know the files you need to mod to do it yourself or if you like the description of what the mod does then you can just add the mod to your game and play
modding isnt hard and adding mods to your game with the JSGME Utility is completely safe and easy to do so dont worry about messing it up