[XML-SIG] replace ENTITY_NODE ?

[Jürgen Schmidt]

This is what the file looks like:

<?xml version="1.0" encoding="latin-1"?>
<!DOCTYPE doc SYSTEM "doc.dtd"
[
<!ENTITY foo SYSTEM "foo.xml">
<!ENTITY bar SYSTEM "bar.xml">
]>
<doc>
   &foo;
   &bar;
</doc>

I would like to change one entity declaration pointing to a different file 
using DOM and write the file back to disc.

thx 

Juergen