Xerces-P Validate subset of a file with schema ?

Hi,

I tried searching the archives for a solution to this, but couldnt find one .. 

I have a file, say :

#test.xml#
<tests>
  <info>
  </info>
  <iWantThis>
   </iWantThis>
</tests>

I want to validate the portion including and beneath  <iWantThis>
using my xsd (schema).

Hence, my schema is declared with <iWantThis> as the root element.

Is there any way to do this in Xerces-P ? Ideally, I would like to
search for <iWantThis> in my document, and taking this as the root,
validate it.

TIA
Abhinav 

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