As of now you must know that you can customize your weapons the way you want in cod4. If you had been lazy enough to miss that, here is the simple step by step tutorial on how to customize your weapons in cod4.
Step 1
Most of weapons are present in iw_04.iwd file (path : call Of Duty 4/main/iw_04.iwd). Open this file in Winrar and you will find list of many game items, scroll down to find the weapon files. For example if you want to skin an AK-74U, drag the file weapon_ak74u_col.iwi to desktop. (path: iw_04.iwd/images/weapon_ak74u_col.iwi) For every gun or any other item you want to design, you must find that particular weapon file with extension “col.iwi”.
Step 2
Now you need to convert this iwi file to a dds one. For this you need a converter that does this simple job and is free ofcourse. There aren’t many out there but here is a simple one that does the job well. Download IWI to DDS Converter Simply drag the iwi file onto that iwi2dds converter and it will convert the iwi file to dds.
Step 3
Now that you have converter that iwi file to dds, all you need to do is customize it as you like in photoshop. But before you can do that you will need to install DDS Plugin for photoshop. After installing you will able to edit the weapon skin just as you are editing an image. After you are done editing the weapon, save it in .dds format as can be seen in screenshot. 
Step 4
Now you have to do the reverse process, coverting this .dds weapon skin to the later .iwi one, for that you will need a converter. Download DDS2IWI Converter Process is again the same, drag .dds file onto the converter and it will automatically convert the file into iwi format. At this you have successfully made a new skin for your weapon of choice. Are you happy ? 
Step 5
Now you need a mode that uses your custom skinned weapons. Go to call of duty 4/Mods/ModWarfare and place your new weapon ak74u_col.iwi in images folder.Now run the makeMod batch file, and it will create a file named z_modwarfare.iwd in ModWarfare folder.
Now place this “z_modwarfare” file in mod main folder (mods/promod2/z_modwarfare) and create a server, load that game mode you just created and enjoy fragging with your customized guns.
My MakeMod doesnt Create a New Z_modwarfare file? when i put the orginal one in there it says I cant make a new one due to theres and already existing file, but when i take it outs fine, when i load, no new file? Help
i think you are not placing your iwi files in the IMAGES folder, or remove z_modwarfare existing file and then try!
hope it will work, ty
but i wanna play in all servers(not just modded server like promod or …)where i have to put that file?
That’s the whole point, you can only play with your skins on servers at which these have been uploaded, not at all servers.
can you make camos for promode plaz tell me
Ye ofcourse you can design them for any mod….
this tutorial is for every mode…