These ebuilds come from http://github.com/joshuar/ephemeral-gentoo-overlay/tree/master.
If you have some problems, go to the official site first.
gpar2 : GUI for verifying and repairing PAR and PAR2 recovery sets ( http://sourceforge.net/projects/parchive/ )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a ephemeral
For Paludis use this rsync : rsync://gentoo.zugaina.org/ephemeral-portage
If you have a problem : ycarus(-at-)zugaina.org