Since no one has replied yet I will give some of my limited input, Ive also got the Chicony USB webcam on my HP. Its a new laptop and the first webcam I have had, but isn't digikam only for actual digital cameras and not webcams? I may be way off with that and they may be the same types of hardware, I havent used digikam software before.
If you are able to fire up Kopete Instant Messanger, it shows an option for webcam. Mine is listed there as HP webcam but it gives me a green screen(bug in kopete or driver i believe). Oh also I have been trying these drivers: http://linux-uvc.berlios.de/
but still have not managed to get my webcam working.
Good luck hope that helps a little at least. everything else on my system worked great out of the box with sabayon!