If a digital camera (still or video) has the capability to be a web cam, it will almost always come bundled with the software that will allow it to act as a web cam. If your camera isn't designed to include web cam functionality, it's very unlikely you'll be able to make it work.
As far as I can tell, the Canon SD600 can't be used as a web cam. Some JVC video cameras can be used as a web cam, but not all. If you know the exact model she has, it's easy to look up the specifications and features of the camera on JVC's web site to see if she can make it work.