Switching manpage generation from docbook-SGML to docbook-xml

Hi,

I'm currently trying to switch git-buildpackage's documentation¹ from
SGML to XML. That worked out nicely for the HTML docs but there's one
problem with the manpages I'm stuck with. I used the build manpages.refs
from docbook2man to get the cross references in the manpages right:

    https://github.com/agx/git-buildpackage/blob/master/docs/Makefile#L64

Now I can't seem to figure out how this works with docbook2x-man. Is
this at all possible? If not are there other tools that can handle this?
Any hint would be greatly appreciated!
Cheers,
 -- Guido

¹) https://github.com/agx/git-buildpackage/blob/master/docs/