xmlwriter and xmlfilter

I am on thesis on archiving *huge* quantities of xml-signed data.
Among other things I have to write a single xml file more than 4 Gb size 
(1 dvd) so I decided to use Sax.

Since the Xerces default content handler does not have a flush() method 
(it keeps everything in memory until the endDocument() method call), I 
changed to Dom4j XmlWriter and then I changed again to Gnu Jaxp 
XmlWriter, because Dom4j does not produce canonalized output.
Now I would like to send the canonalized sax events to a digester in 
order to produce the document hash and then prettyprint the sax events 
into an outputstream (the final file).

First question:
Do you think that I chose the right approach?

Second one:
How can I send the XmlWriter events through an XmlFilter (I would prefer 
not to use the Gnu Jaxp pipeline package: I would like to write 
implementation independent code as far as possible), since XmlWriter 
does not implement the XmlReader interface? Should I extend the 
XmlWriter to do implement it?

Thank you in advance, Bye
Luca Dall'Olio