I don't think there's anything like what you're asking about, and if there were I would think you might end up with input lag issues.
Does your DVD player have aux. inputs? Should be able to go through there.
You didn't specify if you were using the composite cable (the one that comes with the Wii) or a component cable (have to buy it separately). Just as a note, you will get a much nicer picture from the Wii using the component cable.