python binding for xsltSetLoaderFunc

Hello.   I've got a stylesheet I'm trying to run both server side
and client side.  On the client side, I use document() with relative
links to fetch other documents on the server.  Unfortunately, when
I use libxslt on the server (via python binding), the document()
fails to resolve, for obvious reasons.  I can't just make the URL
absolute, since cookies and other items are missing.  So, I was
thinking that SetLoaderFunc might be my savior and allow me to
programmatically return sub-documents that I ask for.  Am I dreaming?
If not, I don't see this xsltSetLoaderFunc in the python bindings,
what do I have to do to get this to work?

Alternatively, I was thinking of making these 'sub-documents'
parameters using document() as the default.  In this way, when
I call the stylesheet on the client, it uses document(), but
on the server end, it uses the entity I return.  The problem is
that I don't know how to take the parameter I return and convert
it into a tree that I can query.  Any ideas here?

Thanks so much,

Cheers!

Clark