Sure 100%. One “issue” with Quartz Composer (actually, ahem, Quicktime) is that some capture devices are not reported when Quartz Composer runs in 64 bit mode. Get info on the QC Editor Application, and select launch in 32 bit mode.
Now you can make a “Video Input” patch, get info on it, and you should be able to select your capture card. Now make a Syphon Server object, and pass the video out of the Video Input patch into the Syphon Server’s image input port. Now name your server if you want, and run the comp. Done and done. For a small performance increase, ensure you have “background erasing” off, even though you are not drawing anything.