Acer's crytal eye webcam is supported by the linux-uvc drivers (http://linux-uvc.berlios.de/)
To install it, just add 'media-video/linux-uvc' to /etc/portage/package.keywords and emerge linux-uvc
It'll install a kernel module that adds support to the webcam, and that's it.
If you want a photo/movie recorder try cheese, it's avaiable at the gentoo sunrise overlay (http://overlays.gentoo.org/ should guide you)
