Instructions
Download two mods for "Call of Duty 4: Modern Warfare." You can download mods for the first-person shooter for free from a variety of file-hosting sites, such as FileFront, GameFront, or Strategy Informer. Once downloaded, the mods will be in a compressed folder.
Extract the files of the compressed folders with the file extraction software of your choice, such as WinZip, WinRAR or ExtractNow. To extract the files, right-click on the compressed folder, click "Extract..." or "Archive..." and click "OK" on the directory you want to install the files to. Any directory will do for now.
Move the mod files to the "Mod" folder located in the "Call of Duty 4" directory of your computer. A majority of the mods for the game simply have to be placed in this folder, but the required destination of the mod is always listed in the mod's "Read Me" file that is downloaded with it.
Start the game and navigate to its "Multiplayer" menu. A number of options will be displayed.
Click the "Mods" option to display all available mods.
Activate both mods to merge the two together the next time you enter into a "Call of Duty 4: Modern Warfare" match.