DOCBOOK-APPS: Please Help: Customizing "titlepage"

All,

I am at a loss trying to customize the XSL stylesheets to behave in a
certain way.
Here's what I am trying to do. I would like the header on the very first
page of a chapter or an article to be different from all the other headers
of the chapter/article. I tried to customize the titlepage.xml file and also
to define additional fo-simple-page-masters. The problem with this last
solution is that I do not know how to tell the stylesheets to use this
fo-simple-page-master for the first page and this other page master for all
remaining pages.
This is a very urgent matter and I would appreciate any help or pointer.

Thanks in advance,

St廧hane Bline.