Originally Posted by tuzmaster_v2
of course there is one way
go to system/app
delete upnxtlockscreen.apk (you should backup it, just in case)
reboot and boom, ICS lockscreen is back
This obviously didn't work, in case anyone is still wondering. I've tried more than I can count.
The way I see it from this guide
, there seems to be a different framework between ICS and JB that prevents the APK from working in JB.
If anyone is still interested, do take note that JB stock in Xperia J and Miro retains the slide-to-unlock lockscreen from ICS, but there are definitely differences also and a direct APK transfer doesn't work at all. People managed to port the JB lockscreen to J, but no one has done vice versa. Perhaps the developer who port it might be able to shed light on this issue.