page xy coordinates for musical events

[Nicola Montecchio]

Hello

I'd like to know if there is a way to get the resulting coordinates 
(i.e. x/y position in cm on the page) of a musical event in the compiled 
ps/pdf file; what I want to do is to typeset a lilypond source, and 
LATER post-process the resulting image. The typical case would be for 
example highlighting a specific bar. Note that I do not want to do that 
directly in lilypond, but as a completely separate step.
I tried looking at the documentation, but could not find anything.
Any hint?

Thanks in advance
Nicola Montecchio

--
Ing. Nicola Montecchio
Ph.D. Student
Information Management Systems Research Group
Department of Information Engineering
University of Padova, Italy
Phone: 0039 049 8277929
http://www.dei.unipd.it/~montecc2