Only one file? If that is the case; I don't think filemon is the way to go as it logs the filesystem so that is many opens and closes you have to contend with.

This sounds like a security issue? Have you thought about running a service and a routine to do that?

You could look at Roths Dirmon script and get an idea. This script monitors a directory for adds and deletes.

May not be what you are looking for but I think filemon will be a moster if I understand what you are after. We have used filemon but we ran it and greped out the stuff we wanted.....