to change the ‘slider text’ download this file:
and search for “slide to unlock” replace it with anything up to 15 characters. once that is done simply put it to /System/Libary/CoreServices/SpringBoard.app/English.lproj/SpringBoard.strings.
While your in the file, you can also change
sync in progress
slide to cancel
slide to power off
super easy to change, and you can change them whenever you want.