Option 1: Get UE4 its 20$ (can cancel sub) and comes with a full PBR setup Option 2: Create a PBR shader using CustomLighting slot (theres a bunch here. I think AlmightyGir posted one up)
The easiest solution would be to just move the project into UE4, there's no PBR in UE3, and the solutions that exist are hacks that don't do it as well. Here's one option http://www.polycount.com/forum/showthread.php?t=124934
Funny you mention that, as I was actually studying that very same blog post when going over all this yesterday. They said they setup their own PBR templates and while I'd love to use UE3 for keeping the engine build authentic, there is absolutely no way I could pull off what they did in terms of lighting. I'm still very…