# get my overlay
as root: mkdir -p /var/db/repos/cttest-overlay
wget https://esl4kids.by/dwnld/cttest-overlay.tar.gz
as root: tar xzf cttest-overlay.tar.gz -C /var/db/repos/cttest-overlay

# configure it
as root: bash -c 'cat > /etc/portage/repos.conf/cttest-overlay.conf <<EOF
[cttest-overlay]
location = /var/db/repos/cttest-overlay
priority = 50
auto-sync = no
EOF'

# install the package
as root: emerge -av app-misc/cttest