More fun integration: Antlr with Stax!
Here's another interesting-looking article, toying with the idea of generating a parser that takes xml tokens (elements, attributes) as its lexical tokens, to parse higher-level constructs. ANTLR is a fine parser generator in its own right, so this could be something akin to peanut butter and jelly meeting to make a great sandwich (even if analogue here may be rather cheesy and naive). :-)
Anyway, in addition to coolness of the almost-recursive use case of "Using parser generator with a parser", this actually seems potentially useful: to me, state machine based systems seem like an obvious way to generate higher level abstractions on top of xml structure. So hopefully someone has time to explore this approach in more detail (I'll have to keep this mind as a potential mini-project myself).