The best thing you'll probably be able to do is use ManyCam to make your desktop a webcam source...then use the DVR maximized on your desktop. Then add the ManyCam source to icamsource.
I doubt it, but you might be able to add one or more of the cams as a source in ManyCam...but that's a long shot.
Another option (which I wouldn't consider much of an option) is to install capture cards that Windows views as a camera source and plug a camera into each one...but that would require 4 empty slots on your motherboard (highly unlikely). I remember several people on here discussing these DVR products, and at most (if I remember correctly), they got one camera working.