These ebuilds come from http://git.overlays.gentoo.org/gitweb/?p=dev/rbu/overlay.git;a=summary.
If you have some problems, go to the official site first.
libvirt : C toolkit to manipulate virtual machines ( http://www.libvirt.org/ )
virt-manager : A graphical tool for administering virtual machines such as Xen ( http://virt-manager.org/ )
xen-tools : Xend daemon and tools ( http://xen.org/ )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a rbu
For Paludis use this rsync : rsync://gentoo.zugaina.org/rbu-portage
If you have a problem : ycarus(-at-)zugaina.org