The do have a kit for the rear VES (video entertainment system) but it is around $1500 + install.
however, if you want to add a video screen headrest or a custom screen and mount, all you have to do is connect the video output to two pins on the back of the radio, (pin 6&7) I think (I will check) and put the DVD into slot number 6 and you will have your video. I will double check the pins but if you search around a bit, I'm sure you can find it as well. I have found a couple of people on several forums that have done the 7" screen mounted above the radio on the dash.