RobotiumForPreInstalledApps

1. Log in as root: adb root
2. Remount: adb remount
3. adb pull /system/app/X.apk (Replace X with the name of the application)
4. Resign X.apk so that it has the same certificate signing as the test project (測試APK的sign需與被測試APK的sign一致。)
5. adb pull /data/system/packages.xml
6. Open packages.xml and remove:
   
   .....
7. Push packages.xml back to device: adb push packages.xml /data/system
8. Restart your device
9. Push the resigned X.apk back to the device: adb push X.apk /system/app

Reference:
http://code.google.com/p/robotium/wiki/RobotiumForPreInstalledApps