[XeTeX] cmyk problem

[Tilman Hannemann]

Hi all,

for a two color process printing, I need to have a cmyk color  
document with only two channels used, i.e., magenta and black. Some  
color switches in my document rely on fontspec's \addfontfeature  
command as they are inside of right-to-left text (an issue already  
discussed here). However, fontspec provides only colors based on html  
definitions of rgb colors. Converted to cmyk, html "magenta" (FF00FF)  
is, of course, made of cyan and magenta. I have tried today a number  
of possible tricks or workarounds, like \maskcolors from the xcolor  
package, but without any success so far. Does somebody of you has an  
idea how to address this problem?

Best,

Tilman