##778# and then you will want to click on edit. The code should be 000000 to unlock from there select view info, select prl and click on update prl file. Browse to the PRL file and once you've selected it click menu and then click ok. Your device should change the PRL and prompt you to reset the device.
If you're looking for a PRL file check out this site:
http://corolada.com/prl/