xsl/xhtml customization layer question

[Michael_Piastro@harte-hanks.com]

I am trying to construct a documentation web site using docbook - this 
documentation is for consumption by our clients, therefore the look and 
feel of the HTML layout needs to be tailored to internal design specs set 
by our creative department. I am trying to do the following using a 
customization layer:

1. Have my "main navigation" correspond to all available <chapter>'s in 
the <book> I'm writing. Navigation items should be able to be wrapped in 
arbitrary xhtml (in this specific case, trying to simulate a horizontal 
row of tabs).
2. Have my subnavigation correspond to all available <section>'s in a 
specific <chapter>.
3. Do (1) and (2) **WHILE** only displaying the <chapter> content for 1 
select chapter  OR section (i.e. using 'rootid' while still getting main 
navigation associated with all the chapters in the book.
4. Ideally, be able to apply different HTML style based on the currently 
selected chapter and section.

Is this possible using a customization layer on top of existing DocBook 
xsl, or do I need to write a custom stylesheet?

Thanks in advance.

michael piastro