Maybe this thread helps you:
Von: firstname.lastname@example.org [mailto:email@example.com]
Gesendet am: Dienstag, 18. Februar 2003 10:05
Betreff: Docbook instead of document-v11?
is there an easy way to use Docbook XML as the documentation type
instead of the new document-v11? We have started documenting our
Cocoon project in docbook but would definitely want to take the
advantage of the possibilities the Forrest project offers (without
having to stop using the authoring environments we have managed to
build for docbook).
Perhaps a XSL style sheet that would transform docbook to document-v11
could do the trick? However, implementing a XSL stylesheet that would
support even most of the docbook DTD and document-v11 DTD would be
quite huge task so we're not able to allocate resources for such
tasks. Instead, we are looking for something more complete (or
faster/easier to implement).