These ebuilds come from https://github.com/mekanix/oomidi-overlay.
If you have some problems, go to the official site first.
openoctave-midi : OpenOctave MIDI and audio sequencer ( http://www.openoctave.org )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a oomidi
For Paludis use this rsync : rsync://gentoo.zugaina.org/oomidi-portage
If you have a problem : ycarus(-at-)zugaina.org