My first thought would be a cable issue. How long is the cable you are using? It will need to be a quality cable if it's over 10ft. The cable is at least partiallly working, as the TV is detected. But that doesn't mean the cable is sufficient.
Aside from that, you simply connect the TV (just like you would any other monitor). No special settings are needed on the TV.
I would suggest moving the TV or computer, and testing with a standard length cable.
S-Video is an option, but only as a last resort. Resolution would only be 640x480, maybe 800x600 if you are lucky.