I wanted to use the RCA jack on my ATI Radeon 9200 under FreeBSD. I discovered that this was very simple. I'll I had to do was boot the computer while the RCA jack was plugged in and the card automatically picked it up and used it. I had display on the TV all the way through the BIOS. X didn't like displaying on the TV when I was using the radeon driver, but the VESA driver works fine with this setup, since it is only running at 640x480 @ 24bit. This skews the display on the monitor to match the display ratio of the TV though. I haven't looked into setting it up so that the displays are different, they are mirrored at the moment.