You need an RS232 port or something like the hardware for a USB to rs232 conversion and then you need terminal software to run whatever hardware you decide on. Then you need the control codes to send to the DVD player.
To increase your chances that it will all work together, I'd decide of the hardware first and get a PCI card with a RS232 port and then talk to the vendor and see what software they recommend to run their card for the operating system you want to use.
A simple google search yields thousands of possibilities.
http://www.google.com/search?hl=en&source=hp&q=rs232+card+pci&aq=0&oq=rs232+card&aqi=g7g-m3
Then you need to worry about the control codes you need to send.
http://www.remotecentral.com/cgi-bin/mboard/rc-touch/thread.cgi?1455