Hair and Fur Custom Shader setting scripting help


Has anyone here written MAXScript dealing with the Hair and Fur (WSM) setting "Custom Shader" section? I'm currently using MAX2018 and can manipulate the "Apply Shader" check box with no problems, but I can't figure out the scripting for selecting a specific material from a previously loaded materials library is done. When I manually select a material with the custom shader setting, I see in the listener window shows:

"$MyObject.modifiers[#Hair_and_Fur].MR_Shader = Standardmaterial ()"

I am aware that the "MR Shader" setting is/was related to Mental-Ray materials, but as I mentioned, I can select pretty much any material here and it works as expected. I just can't seem to script it. Even if I take that line from the listener and run it, it causes an error "Invalid value for property: Standardmaterial:Standard" in this example.

Any help or workarounds will be much appreciated.