I've seen a camo pack like this before.. It was uber gay; and not proper.. I've remade these myself; it contains the camo image, menu camo image and the small menu preview while selecting it.
Just extract the images from the iw_06.iwd folder to the iw_06.iwd/images in your main Mw3 folder which you opened with Winrar. hope you understood this tutorial, it's too early for me.