[development] Intercept menu calls

Hi, I want to add some code to the menu system, in a way that I can add new menu items with a special format: 1. the path will allow to accept regular expressions 2. the items have the option to be saved or not inside the database This is something that has to do with issue http://drupal.org/node/120521 but that I'm trying to implement in D5 (I really need them). So, what I need? Just a way to intercept menu.inc inside functions, in a way that will allow me to execute my validations, menu builds and routing. Feasible? Any idea? Regards, Fernando