Item description:

This map is meant to be used as a multiplayer map for the "Zombie Survival" gamemode.

Just throw the BSP file included into the "C:\Program Files (x86)\Steam\SteamApps\common\GarrysMod\garrysmod\maps" folder.
I'm afraid I don't know how to set this up in a server rotation, but it shouldn't be any different from any other map.
If you find any problems, or have any suggestions, tell me. I greatly appreciate it!

This map may be subject to change.

EDIT (2014/02/23): I've just modified the BSP file so that the soundscapes should play as intended.

EDIT (2014/02/27): I've modified the BSP again, now I'm certain the soundscapes work (sorry).