Running boost book from outside the boost directories

I'm working on a project where I want to use quickbook/boost/book outside of 
the boost directory tree.

>From the documentaion:

Once BoostBook has been configured, we can build some documentation. First, 
change to the directory $BOOST_ROOT/doc and remove (or make writable) the 
.html files in $BOOST_ROOT/doc/html. Then, run bjam to build HTML 
documentation. You should see several warnings like these while DocBook 
documentation is being built from BoostBook documentation:

Which begs the question of how one can do this for anything that is not 
inserted to the boostbuild tree.  How do I go about building documentation 
with boost tools for a project which is not inside the boost tree?

Robert Ramey