Extending Group Policy Preferences
The Group Policy preference extension is designed to allow developers to extend the Application preference item. For those applications that are currently unsupported by Group Policy preferences, you can create your own property sheet extension for the Application preference item.
And we have added some instructions for how to do this in MSDN. For more information check out the topic, "About Group Policy Preferences", http://msdn.microsoft.com/en-us/library/cc512161(VS.85).aspx.
Judith Herman, Group Policy Programming Writer