Numark318i,
It was pretty simple to get 7" monitors into the headrests. First you have to take the hardware part of the headrest and slide it out of the cover and foam. After that you take the foam out of the headrest cover and place it over the hardwear part. Next, fit the headrest monitor shroud over the foam and make the cut on the foam to fit the shroud only. Next you place the headrest cover over the hardware, foam, and shroud. Lastly, you cut in an "X" pattern about .5 inch from the shroud, cut the excess, fold in some of the headrest cover and place your monitor in the shroud.
Its pretty simple. It only take me about 5-10 minutes per headrest.