Including Servlets/JSPs in templates

Hello,
I need to be able to include a Servlet or JSP from inside of /templates/*.vm files (specifically header and footer).

I tried things like:

$request.getRequestDispatcher("/xxx.jsp").include( $request, $response )

But for some reason (buffering in Velocity I guess) it renders included page before anything else, no matter where it's actually placed. Is there some workaround? If not, I think I have an idea how to implement a kind of "#includeServlet" directive, could it be included in XWiki then?

Greetings, Lilianne E. Blaze