Instructions
Start up the "Call of Duty: World at War" game.
Go into "Nazi Zombies" mode. Select the options for your game and begin. Make sure that the console is enabled in the option menu.
Toggle the console by pressing the "~" key. This will bring down the in-game console where you can type in commands to make modifications to your game.
Type "give zombie_melee" into the console. You can also type in "give all," which will give you all of the weapons, but that would require you to modify the map by using a "devmap" version that allows hacks and cheats.