The DCDigital (Formerly DCHDMI) doesn't interfere with analog/VGA output of the console. So it'll still output as normal. The lightconn plugs into the controller port for power and bluetooth, grabs sync from a tiny wite running out of a VGA adapter, and a wii sensor bar provides the InfraRed light sources for triangulation of the wii sensor in the lightgun. If I remember correctly, the VGA just needs to be plugged into the console. I'm not sure if the other end needs to hooked up to a TV or not. I always have mine hooked up to my OSSC via VGA and from the DC Digital out port to my TV via HDMI.
That works, if you're far enough back from the TV for the IR camera to see the whole screen and calibrate. There is lag, just like a Wii remote. So don't expect a miracle. If you need a wider angle, you can use a cell phone wide angle lens. It affects accuracy, but allows you to get closer to the screen.