StAX parsing is just another way of reading an XML document as a sequence of events where each event represents a logical part of the document.
The real question is - where is the modified document supposed to go?
Are you writing to a new file, event by event? Perhaps you are ending up with a DOM memory object representing the document and the fact that StAX is involved is not significant.
Harold's chapter (free) on event processing may be helpful.
Bill