If your TV set is equipped with a Euro-SCART input then things are much simpler... All amateur radio stores and bulk electronic shops (even some super markets) have two-way adapters from S-video (also called YC-component) or composite video (RCA connector) to SCART...
Use the link that Klug supplied, it is the most simple solution I have seen yet!
If you want to be creative you could buffer these signals, then combine then and restore the DC level to 1v p-p before deliver to the video input on your TV.
But Klug solution 1 parts, or get creative add another 30 or so discrete parts for not so much improvement.