Adding content to div class="article"

Hi,

I use Docbbok to create online help. Each HTML page corresponds
to a single article. My customization layer uses templates like
user.footer.navigation or user.header.navigation. However, that's not
enough to properly lay out the contents of a page. My custom XSL
transforms must add some div elements inside the div class="article"
element. How can I do that?

Thanks,

Robert