Using XERCES with XPath support

Hello,

I have an application relying heavily on XML. I am currently using MS-XML4.

The application imports, builds, changes and exports XML documents and 
uses XPATH to find notes. The main reason for switching to XERCES is 
using Apache XML Security later.
I am trying to migrate the application, I started with XERCES and then 
found out it has no XPATH support. I continued with XALAN but it does 
not allow to change the XML and if I use a wrapper I will need to 
rebuild it after each XML change.
Do, where do I go from here?

Thanks,

Reuven Nisser