How do I load str into DOM

Hi All

I have written some C++ code that loads an XML file using Xerces DOM
from an XML file and does some stuff with it. I would like to be able to
do the same thing but from a string instead of a file. How on earth do I
do it? 

This seems to me like a lame question. However, I can't find any
examples or documentation that describe how to do this.

Thanks in advance.

Nick