FFFFFFFFFFFFFF! I got it to work too! But there's a catch.
I followed everything OP did EXCEPT to try and install on SD Card. I moved the Lockscreen.apk to SD Card, rebooted, and nothing happened.
I did this again, but now I attempted to install the Lockscreen.apk and of course it fails. Rebooted the phone and stock lockscreen!
Moto X & Nexus 7 2013
Current Daily Driver:
Motorola Droid X | Motorola Droid Razr HD | Samsung Fascinate | Asus Transformer TF300T | Samsung Galaxy Note 10.1 | Samsung Galaxy S III | Samsung Galaxy Note II | Asus Google Nexus 7 (2012) | Verizon Galaxy Nexus | T-Mobile Samsung Galaxy S4 | HTC One