That's simply not going to work. We print separations from over a hundred documents each day and each one has a different set of Pantone spot colors in it.
I can get the list of those colors easily enough through the script, it's just a matter of telling the print dialog, "Turn off all separation colors except the ones in this array variable." Is there a way, perhaps, to have the script automatically create a temporary custom preset with those separation colors active, then delete it afterward? Or perhaps just have the script overwrite that preset each time it is run, with the appropriate separation colors for the document it's being run on?