How to use Serghei's overlay?

Hello to all. I've found this overlay: https://github.com/serghei/gentoo-trinity-overlay How do I use it within Gentoo? I've installed layman and of course "layman -L" doesn't show it. Can anyone tell me how to make its ebuilds visible? I've also tried downloading from this link: https://github.com/serghei/gentoo-trinity-overlay/zipball/master and making a local overlay, but that didn't work -- only kde4 packages showed up in emerge --search. It's possible I have something masked, but I'd think if I had the overlay set up correctly, that they would show up in the search, just marked as uninstallable. I don't need the whole TDE desktop -- I only want to get kpdf and gwenview working. Thanks in advance for any suggestions or explanations. Tony