This is a tool I've created that will allow you to censor, uncensor and launch L4D2 with a click of a button (technically 3).

http://www.box.net/shared/8gle19y4l4

Either drop that into your left 4 dead 2 folder or anyother location and follow the instructions in the "directory.txt' file.

Check it out here:
http://www.l4d2.upc-gamers.com/download.php
I'm going to be playing them quite a bit so if you guys wanna download it, we can all play together.
Put the required files into your addons folder and then download the maps.