Single package for OS 9 and X?

[RGould8 at aol.com]

Is there a way I can make a Mac OS X Revolution app, that, when someone 
attempts to run it on Mac OS 9, will display a popup saying "This application is 
designed to work only in Mac OS X".   Right now, OS 9 users just see folders 
(which is what I would expect).   Somehow Mindvision VISE has a technique for 
making some sort of "combo" file that works in OS 9 and OS X at the same time - - 
- was just curious if the same technique could be applied to Revolution.