Just drop the .vpk in your addons folder and that should do the trick. If it doesn't work then, I don't know what the problem could be as it works just fine for me as seen in the video.
This mod was created thanks to Audacity's ability to apply the same effect to multiple sound files automatically. And even with that it took around 2 hours to mute all of them. I hope people like this, I did the work for you. So you don't have to suffer like I did.