Okay so you have a video camera that you are using as a CCTV camera and you want to use the attached screen of a portable DVD player as the monitor?
Firstly, you can find a composite input monitor for really cheap. eBay my friend EBAY.
http://www.ebay.com/itm/JVC-TM-900SU...item3f13e0d51c
Secondly if you want to go the hack route then model numbers or chipset numbers help.