Default [Q] USB webcam as default

Hi guys

I recently found out how easy it is to connect your USB webcam to the Nexus 7 & use it as a camera using the Simplewebcam or DashCam applications.
Now I would prefer to use one of the feature-heavy dashboard camera applications in the playstore, however these always use the internal camera.

So my basic question is: is there any way to trick the Nexus into thinking the USB webcam is actually the built-in camera?

Thanks in advance!