Well CF, like HTML, is a static medium so you wouldn't
actually do that in CF.
There would have to be some clientware required (Flash,
Shockwave, Java, ActiveX, etc) that could connect each client's
webcam to the web. These in-turn could be run and processed via CF
or HTML for a website.
The connectivity for the webcams comes from the actual client
interfaces though, and many times these are proprietary. I know of
a widget for Shockwave that may help, but it's usually used as a
desktop app. You could also check with various webcam vendors (like
Logitech etc) and see if they have an SDK for such things.