As a thrid party, you only know when a specific deployment is happening when you have parsehandlers in place at the moment it's parsed. No way to hook in "before" parsing. What about making your parsehandler smarter, and ignore processes that you're not interested in?
Or make a single (always added) parse handler that is called for each deployment and, if needed, can execute additional logic, based on an internal list of 'dynamic handlers' that can be updated before passing on control to those classes? (kind of a dynamic delegation pattern)