DOCBOOK-APPS: color coding

Hi,

I am using DocBook to write technical documentation for our system. In that
documentation I have included a lot of program listings (mainly listings for
OmniMark programs and their HTML output).

I would like to process those program listings and output to html/xml:fo
with color coding. Are there extensions to the XSL stylesheets that can
apply such color coding or should I write them from scratch?

All help is greatly appreciated,

Arjan Huijzer