Identifying exactly where on the page a musical element occurs can be extremely difficult in musicxml. The layout.py module of my music21 python toolkit (shameless plug) can do it up to the measure level -- getting the note/credit level will not be too hard after that. The code is LGPL so you could use that to hack together a parser in another language.
See http://web.mit.edu/music21/doc/moduleReference/moduleLayout.html#music21.layout.divideByPages