NOTICE: THIS HAS ONLY BEEN TESTED ON CM10. IT MAY OR MAY NOT WORK ON OTHER ROMS.
Update: Alarm clock now works! All you have to do is clear the data for the original clock, delete it using a root explorer, and then flash the JB clock in recovery.
Make sure you wipe cache in mounts and storage, and wipe dalvik cache before you flash it. You can also do a nandroid backup just to be safe, but I doubt you really need to.
I recommend you use the apk if you are trying to install this on a non-jellybean ROM. If you are going to flash it, make a nandroid backup first.
Apk (Move to System/app):
Thanks 'TheDarkDefender' for porting this
Edited by kyan31, 14 December 2012 - 07:23 PM.