LyX ⇒ How to produce a good CMYK pdf file in LyX

[Gumbare]

Hi all,
I'm completely new to LyX (and LaTeX).
I have written a book with black text and several black&white (grayscale) graphics. I can have that graphics in whatever format they are required.

Let's say I have everything ready and... I need to export (save, print) that book from LyX into pdf with CMYK color space so the ink in print shop is taken only form black (K) palette.
How to do that? How to export pdf in CMYK?

thanks in advance