sdlmame : Multiple Arcade Machine Emulator + Multi Emulator Super System (MESS) ( http://mamedev.org/ )
xmame : Multiple Arcade Machine Emulator for X11 ( http://x.mame.net/ )
xmess : Multiple Arcade Machine Emulator for X11 ( http://x.mame.net/ )
Add an ebuild in portage :
The ebuild is now in the portage tree.
You can also use layman : emerge layman then layman -a mv
For Paludis use this rsync : rsync://gentoo.zugaina.org/mv-portage
If you have a problem : ycarus(-at-)zugaina.org