disabling focus stealing in Mac OS X?

Solution 1:

AFAIK, focus on OS X is dictated by the application doing the stealing as well as the application which currently has focus (it is possible, for example, to program an "autocratic" UI application, such as a game).

That said, it may be practical in your situation to modify the focus-stealing app itself. Inside the app bundle is an Info.plist. Add the LSUIElement key and set it to 1. This will (should) remove all trace of UI or dock icon, though it will still be visible in activity monitor.

If you need to interact with this app's UI on a regular basis, this probably isn't practical. It might be just what you need, however, if you don't need to do more than launch it. Assuming it works with that app, that is.