Have you considered asking your development team to have a "no dialog" mode of the app for testing purposes? Perhaps if you stopped referring to them as (!!*&%) they would be more inclined to partner with you. ;) Afterall, you do work at the same company on the same product :)
In any case, without a dev-specific solution, consider having a another app (process or thread) that continually sleeps for a few seconds, wakes up and looks for a modal dialog in your application. You can use APIs such as FindWindow to identify when a modal dialog has popped up. (Use Spy++ to get the class name for windows created by MessageBox and CreateDialog APIs).