Pure android, impossible you must be rooted and must have and unlocked bootloader but you can get very similer ui with apex launcher, and by re installing the xperialockscreen.apk in sytem files then turning off and on again to get an almost pure xperiance, you can also get all of the stock android apks from google play if you look hard, trust me i know and btw if you want to get your xperia lockscreen back then just go to settigs,apps then uninstall xperialockscreen.apk back to factory edition and then reboot or what ever but to flash the xperia 4.2.2 Of coarse it is possible! That is how i have 4.2 on my phone, aslong as you are using a legit firmware to flash otherwise you may be downloading the worng thing which could probably do some serious harm to your phone, I suggest using this as this is what i flashed! Hope i could help Give me some positive feed back it took me ages to find this again http://forum.xda-developers.com/showthread.php?t=2336874
