avevo trovato questo su xda.... ma riferito a ics:
"Well. OK, but only for who doesn't frigthen himself to use a hex editor and has root, cwm, and so on...
If you have a modified rom or you're about to load one in your phone, you can also do this mod directly in the zip file of the rom.
In every case, in the folder system/framework you can find the file framework-res.apk. Copy it on your desktop, change its extension to .zip (you know it) and open it. In it you'll find the file resources.arsc. Well, open it in a hex editor and "search" the phrase "Swipe to unlock" in your idiom. Change the very first byte of the phrase to hex "00" and eventually all the others to "FF". Save, close, revert the extension to the original ".apk" and copy the modified file over the original. Reboot and voilà, your lock screen is now clean..."
Ci ho provato e funziona, solo che dopo questa modifica, tenendo premuto il pulsante power, si spegne direttamente in cellulare e non esce più il menù con le varie opzioni (connessione dati, modalità silenziosa, accessibilità, spegnimento...)