R plots pdf() does not allow spotcolors?

Scribus claims to be able to convert RGB/CMYK colors to spot colors:
http://documentation.scribus.net/index.php/Spot_Colors

I've never used Scribus, but it's floss.

Scribus can import output from R's svg driver (with at least some
degree of success).

 I just imported a simple plot to Scribus, specified some spot
colours, and saved as EPS - the colours were specified as /Separation
colours as described in my earlier message.

 I did try inkscape for this, but forgot about scribus. Inkscape
doesnt seem to have such colour management.

Barry