You could get the World at War zombie maps if you pre-ordered a special edition. The multiplayer maps are not available.
You cant get it because it is not available for purchase anywhere.
Call of the Dead is available only with purchase of the Escalation DLC
Call of Duty: Black Ops is available for purchase at the following locations in the US: Gamestop, amazon.com, Walmart, steampowered.com, direct2drive.com, and store.activision.com.
Only Call of Duty World at War and Black Ops have Zombies and with the release of Rezurrection Map Pack for Black Ops all 11 Zombie maps are available for purchase with Call of Duty Black Ops and the 4 DLCs for the PC PS3 and Xbox 360 versions of the game
For the standard WAW edition there are 3 DLCs available for purchase besides the single zombie map included after the game is completed. They each include an additional zombie map that is only available with purchase of the map pack. The modified Black Ops WAW maps are only available on the standard Xbox 360 edition of Call of Duty Black Ops with purchase of the Rezurrection DLC or Map Pack.
Uprising is now available for PS3 players to purchase.
from black ops website
You can purchase the Call of Duty World at War Zombie map 2 different ways from the Playstation Store. One set is modified and updated with Black Ops weapons and redesigned for Call of Duty Black Ops and also includes a another Zombie map Moon. That can be purchased for $15 from the Playstation store as the Rezurrection Map Pack. You can also purchase the World at War DLCs for $10 each or in a bundle for $25 from the Playstation Store
Ascension must be played on Call of Duty Black Ops and is one of the maps that you receive when you purchase the First Strike Map Pack for $15. It is not available for purchase except in the First Strike Map Pack and can not be played without Call of Duty Black Ops
You purchase the hardened or prestige edition off the game
Zombie mode for call of duty is only available in World at War and Black ops and it is found in the start menu.
You can not. There are no Map Packs for the Call of Duty Black Ops Nintendo Wii version of the game. The Nintendo Wii Call of Duty Black Ops was also not available in the hardened or Prestige Editions of the game with the maps from Call of Duty World at War because those maps were never available for the Nintendo Wii. The Hardened and Prestige Editions of Call of Duty Black Ops were only available for the Xbox 360 and PS3 because they were the only consoles that had Call of Duty World at War Map Packs 1 through 3.