Twilight's Zombie mod is available to the PUBLIC. That's right. You heard right. The RVSZombie mod is ready for download. You can read more on it at RSVGaming. And you can download it at Twilight's ModDB Zombie Mod site - click here.
The download comes with files for SP (Singleplayer), MP (Multiplayer), and the Source Code. Plus an easy-to-read instructions on how to install the mod as well as EDIT it for your personal customization.