iSight difference MAX patch

Hey,

I have just been approached todo an installation which needs to be done for tomorrow ... was wondering if anyone had the barebones of this already as I'm on such a tight time constraint ...

I want the output of an iSight to control the speed of a sample being played back (a pulse sample), so using the difference between frames to control tempo. Fairly simple but I'm fairly new to Max :)

Thanks in advance!