The CVS jboss head used to have (and the new SVN head still has) a docbook-support subdirectory.
What is the recommended way to use it to build a separated project documentation: copy it over into project's SVN repository, download it from repository.jboss.com (where currently it isn't) or some other way?
The easiest thing to get you going for now is just to check out the doc-book support project alongside your own.
svn co https://svn.jboss.org/repos/jbossas/trunk/docbook-support
This is how jboss-cache, for example, currently operates.
It might make sense to have this become a standalone project and be integrated via binary support in the long-term.....