DOCBOOK: customizing docbook xsl

hi there,

I'd like to modify the html generating xsl a bit so I'm
looking for advice on where to look for the templates I
need to override:

I want to generate a framed html, similar to this picture:

http://d3e.sourceforge.net/screens/d3e-ui.jpg,

with the main document in one frame (chunked, probably),
and the toc and some other meta info in separate frames
(the main new thing being some embedded cgi to attach
issues (commands for now) to sections of the document.

Any advice or comment is highly appreciated !

Regards,
		Stefan