oh, yes, setmapping will load the corresponding module, but with most video capture software running on your host, they will request a given video resolution when they start, which will in essence issue another setmapping again.
So, to change which module runs in the camera, you just need to select the appropriate video resolution in your video capture software. For example, if you set your video capture software to 640x300 YUYV, this will load and run DemoSaliency in JeVois.
Please see http://jevois.org/doc/UserQuick.html
at the bottom of the page for links for how to get that going with Windows, Linux, and Mac hosts.