Parse an XML document from a given SAX event producer

Hi, 

I'm new to libxml/libxslt and I wonder if it's possible to parse a
document (create a DOM) not from a character-stream, but from a source
of SAX events. I'm currently looking at reimplementing the XSLT
processing for the LibreOffice XSLT Filters using libxslt (currently
implemented in Java using Saxon), and the filter framework doesn't
provide character-streams as document source, but SAX events. I'd like
to write a simple wrapper that translates the LO sax events to libxsl
SAX events. Is that possible (and desirable, too)?

Thanks, 
Peter