Instructions
Open the "Config.cfg" file found in the "Players" folder of the "Call of Duty: Black Ops" directory. This directory will vary depending on where you installed the game's files, but, by default, the file path is "C:\Program Files\Activision\Call of Duty Black Ops." You will need to open the "Config.cfg" file with a text editing program, such as "Notepad."
Change the line "seta monkeytoy 1" to "seta monkeytoy 0" and save the file. This will allow you to access the game's hidden console.
Boot "Call of Duty: Black Ops" and start in match in Zombie Mode. Once the game loads, you will be instantly placed in the level.
Press the tilde key (~) to activate the console. A new window will appear, which will have a text box at the bottom where you can enter commands into the console.
Type one of the game's cheats into the console and press "Enter." The three cheats are "/give all," "/noclip" and "/god," and they should be entered without quotation marks. The cheats will give you all the game's weapons, allow to you walk through walls and make you invulnerable, respectively.