Looks like the include/exclude list or the dialogue is not exposed to maxscript. To create a custom button we would need that (like it was done with showLightMixSetupDialog).
So you would have to sumbit a feature request for either a max function to call the material override setup settings (like LightMix) or to expose the include/exclude list (which is the last material override item missing, everything else is accessible by maxscript already, don't know why the node array is still missing).
Good Luck
