Ok. So there's a tweak in Cydia that pretty much works the same way as PerPageHTML but for you LockScreen. Has some neat features as well. Here's how you use PerPageHTML widgets with it. So just place the PerPageHTML widget in var/mobile/library/LockHTML. Open the theme folder and you will see a document labeled widget.html What you want to do is rename it to LockBackground.html and that's it. The theme is now useable with the LockScreen tweak. Works the same with LockScreen widgets theme selves as well. May need a respring.