These ebuilds come from https://gitlab.awesome-it.de/overlays/piwik.
If you have some problems, go to the official site first.
piwik : Piwik is a downloadable, open source (GPL licensed) real time web analytics software program. ( http://www.piwik.org/ )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a piwik
For Paludis use this rsync : rsync://gentoo.zugaina.org/piwik-portage
If you have a problem : ycarus(-at-)zugaina.org