The key here is to use the CED utility and on the SDVO Port Page, go into the CH7022 (same as a CH7021) attributes and changing the "Display Type attribute (ID 9) to Composite or S-Video which are both TV modes. When you do that, you will have a sample xorg.conf section for the IEGD parameters that contains something like this:
Option "ALL/1/Port/2/Attr/9" "4"
(this example sets it to composite by using option 4, if you set it to 8 then it will be S-Video)
Hope this helps.