[pdftex] pdfcolorstack?

[ivo welch]

dear pdftex-perts:  (also posted to comp.text.tex in a form).  are
there some examples of the use of the pdfcolorstack primitive?  I want
to replicate the functionality of

\special{color push}
\special{color cmyk 0.0 1.0 0.0 0.0}
This should be red.\par
\special{color cmyk 1.0 0.0 0.0 0.0}
This should be blue.\par
\special{color push}
\special{color cmyk 0.0 0.0 1.0 0.0}
This should be yellow.\par
\special{color pop}
This should be blue again.\par
\special{color pop}
\bye

I understand I can do so by including the color.sty package, but I am
afraid it may be overkill and run into some conflicts with other
stuff.  fortunately, it seems that the functionality is exactly what
pdfcolorstack would do.  unfortunately, I cannot find a good example
of its use online.  the pdftex manual that I have is from Jan 2007,
and so it is a little dated.  (no, I am not complaining at all.  you
guys are doing a great job pushing it forward, even if the docs
sometimes lag a little.)

regards,

/iaw