The emerge command I use:

$ emerge-tatl fake-package-name

The ">>> Install" step will take an enormous amount of time (minutes!) and spit out some warnings. This is one of them:

readelf: Warning: Section '.GCC.command.line' was not dumped because it does not exist!
File not built with -frecord-gcc-switches: /build/tatl/tmp/portage/<snip>/lib/libpty/linux/x86_64/libpty.so
File not built with -Wl,-z,now: /build/tatl/tmp/portage/<snip>/lib/libpty/linux/x86_64/libpty.so
File not built with gold: /build/tatl/tmp/portage/<snip>/lib/libpty/linux/x86_64/libpty.so

And then at the end it will spit several messages like this:

* QA Notice: RESTRICT=binchecks prevented checks on these ELF files:
* /<snip>/lib/libpty/linux/x86_64/libpty.so

To be fair to the binchecks, they aren't wrong, as these binaries are all downloaded prebuilds that are unlikely to be up to the standards of an local ebuild compile. It's annoying that I explicitly disabled these checks AND they happened anyways at great length AND emerge has the audacity to tell me that the checks were prevented.

Relevant ebuild with the names changed to protect the privacy of the innocent:

EAPI=5

RESTRICT="strip binchecks"

DESCRIPTION="Silly Package Description"
HOMEPAGE="http://example.com/fake-url"
SRC_URI="fake-src-uri.zip"

LICENSE="WTF"
SLOT="0"
KEYWORDS="*"

S="${WORKDIR}/fake-package-name"

RDEPEND="x11-base/xwayland
	app-arch/unzip
	media-fonts/roboto
	x11-libs/libXrender
	x11-libs/libXtst
	x11-libs/libXi
	x11-libs/libxcb
	sys-libs/zlib[abi_x86_32]
	app-arch/bzip2[abi_x86_32]
	sys-libs/ncurses[abi_x86_32]
	sys-libs/gcc-libs"

src_install() {
	insinto /opt/fake-package-name

	doins -r *
}