I have, or rather had, the same feature in one of my apps... From all the research that I have done this feature is no longer possible.
The SDK Docs state this about why the restartPackages permission was deprecated:
"This is now just a wrapper for killBackgroundProcesses(String); the previous behavior here is no longer available to applications because it allows them to break other applications by removing their alarms, stopping their services, etc."
This seems to imply that anything visible to the user can no longer be closed by SDK applications. I am very disappointed by this decision and if anyone knows of a workaround I am interested in the answer as well.
I understand that there is the potential to "break" other applications with this feature enabled, but I thought that this is what the whole permission system is for. Users know up front the permissions that the app grants and thereby know what the possible consequences are.
I don't know how many people have come to me asking me to fix the fact that they can no longer close applications in FroYo via my application.