Not exactly.

You want to control the brightness of the diffuse light by multiplying it with the ambient occlusion.

There are two ways.

One is to use a Color_Math node, both values white, set to Multiply. Connect Input_1 to the original shader tree that goes into Alternate_Diffuse. Connect Input_2 to the AO node. Connect the Color_Math:Multiply to Alternate_Diffuse. However, this may not be the "best" way, if the shader also calculations reflections, refractions, or specular highlights. Ambient occlusion should not darken these calculations. It should only affect diffuse lighting.

The other is to go through the shader and find where its using a diffuse lighting node, such as Diffuse, Clay, Skin, Velvet, etc. Then just plug the AO node into that lighting node, using whatever input channel controls the brightness. For Diffuse, that would be Diffuse_Value. The AO node is at the bottom.

The attached screen shot is of one of my complex skin shaders that goes into Alternate_Diffuse. I grabbed this from another thread and it has many annotations that are not relevent here. The one you care about is #6. That is where my AO node is plugged in.

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