Install Inkscape 0.47 pre release:
http://webupd8.blogspot.com/2009/06/download-inkscape-047-pre-release.html
Wow! This is mind blowing!
To get quadrichromical images from Inkscape, our "rock in the shoe" way is to save vectorial drawing in SVG, and import it in Scribus. To get the right colors, we recompose …