does anyone know how to get multiple mental ray nodes like mia_material and the sss shader onto one object without actually blending them in?

i tried doing this by using the layeredshader node (because the mib_color_mix didn't have an option for transparency), i plugged in the mental ray node's colours and gave it an alpha map and it worked ok... except for the final result not being the same as what it would be if the mental ray node was connected straight to the shading group