EbuildMode is for editing Gentoo Linux ebuilds and eclasses. It is maintained by the Gentoo project and is installable from Portage using the “emerge app-emacs/ebuild-mode” command (or “emerge app-xemacs/gentoo-syntax” for XEmacs). If you wish to obtain EbuildMode without using Gentoo Linux the source can be downloaded from: http://gentoo.osuosl.org/distfiles/ebuild-mode-1.22.tar.xz. You can use the autoloads and auto-mode-alist configuration from Portage for your .emacs configuration.