More information can be found here: ForestryMC/ForestryMC#441

Does it work with custom renderers or will that need to be disabled? My ores already do overlay rendering.

I'm not sure about it. Try to ask Zeno410 about it. He should know better.

Handled by http://minecraft.curseforge.com/mc-mods/227992-ubc-ore-registrar now.