[R] R plots pdf() does not allow spotcolors?

[Matthieu Stigler]

Hi

We are about to publish a book, which contains figures made with R 
plots. An important detail that we did not take into account is that the 
book will not be printed in 4 colors (cmyk mode), but only 2 (black 
+"spotcolor"). The spotcolor we use is part of the big Pantone family.

The problem is that both pdf() and postscript() offer either rgb or 
cmyk, but no spotcolors such as pantone. I'm afraid this constraint 
can't be solved at all, and we can't use R for creating these plots? I 
did not find any package that would extend the colormodel to include 
spot colors... Did anyone had a similar experience?

Thanks!!

Matthieu