Use desktop as camera on Mountain Lion Hopefully this is not too difficult;

I have an Elgato Game Capture HD, which I am using to capture an HDMI signal. What I want to do is take either the onscreen capture window or the USB signal into the computer and use it as a camera on OS X Mountain Lion in ProPresenter 5.

I downloaded Desktop Presenter, but I do not know where the signal from the program is going to, nor do I know if this will even act as a camera. 

Any suggestions? It needs to be recognized the same way the FaceTime Camera is recognized (as a camera).
What you're after is a virtual webcam software, such as ManyCam:


  
  Draw over your video window or screencast your desktop online with our software for your webcam