I feel like I'm missing something small, but I'm trying to set up a material that uses an ambient cubemap for ambient lighting. It took me a while to figure out how to set up the orientation, but now I can't figure out how to apply it properly. I've tried multiplying it with the diffuse map into the diffuse channel, but it comes out too dark. I've even tried popping it straight into the emmissive slot, but then part are supposed to be black in the diffuse still show us pretty light.
Can anyone help me out?

Have you tried multiplying the cubemap with the specular map before plugging it into the emissive slot?

Just tried it. The spec map show up in the emissive way too much.

Maybe multiply the ambient cube with a constant less than 1.0 (to make it darker) then add that result to the diffuse or plug it into the emissive.

Ambient light by it's nature will brighten shaded areas, so you shouldn't end up with dark/black shadows.