This is my new Portage tree overlay.

You can add it with eselect repository:

eselect repository add getburning git https://github.com/GetBurning/getburning-overlay

Or with a configuration file in /etc/portage/repos.conf/:

[getburning]
location = /var/db/repos/getburning
sync-type = git
sync-uri = https://github.com/GetBurning/getburning-overlay

Or just copy things to your own overlay.