[Gimp-user] CMYK + additional color layer?

[Kristian Rink <kawazu428 gmail com>]

Folks; 

done a modestly complex flyer layout which, by now, should be printed by a 
professional service. Unfortunately, those would like to have a CMYK PDF 
image, including an additional layer for a "highlight" color (which should be 
gold or silver, not sure yet).  I've done a bit playing and, so far, am unsure 
about whether (and/or how) such a kind of pre-print color separation can be 
done using GIMP, or whether I would have to do this in another way. Any 
thoughts, recommendations, ... how to get my xcf stored in a way feasible for 
this kind of printing?

TIA and all the best,
Kristian