Install this version:
emerge -a =app-emacs/volume-9999
If this version is masked, you can unmask it using the autounmask tool or standard emerge options:
autounmask =app-emacs/volume-9999
Or alternatively:
emerge --autounmask-write -a =app-emacs/volume-9999
# Copyright 1999-2022 Gentoo Authors
# Distributed under the terms of the GNU General Public License v2
EAPI=8
inherit elisp git-r3
DESCRIPTION="Tweak your sound card volume from Emacs"
HOMEPAGE="https://github.com/dbrock/volume-el"
EGIT_REPO_URI="https://github.com/dbrock/volume.el.git"
EGIT_BRANCH="master"
EGIT_CLONE_TYPE="mirror"
LICENSE="GPL-2+"
SLOT="0"
KEYWORDS="~amd64 ~ppc ~sparc ~x86"
# NOTE we might define the following which volume.el can work with by
# default, but volume.el can really work with anything.
# RDEPEND="|| ( media-sound/aumixer media-sound/alsa-utils )"
SITEFILE="50${PN}-gentoo.el"