Importing Shader Builder macros

I've yet to see any documentation or even a post mentioning this. So far, I've figured out that you need to use the Shader Builder macro brick in Shader Mixer then load the chosen macro exported from Shader Builder. The shader inputs translates just fine, but the brick basically don't have any input at all.

This is using a copy of Shader Builder 'Specular' macro. But even just using a constant color value doesn't seem to work at all. Anybody ever succesfully imported Shader Builder macros into Shader Mixer?