Hey, I recently unlocked a Blackberry Curve 8310 from Rogers for my girlfriend, here's the instructions I followed:
How to Enter Unlock Codes on BlackBerry Bold, 8800, 8820, 8300, 8310, 8320 and 8900:
Note: NO SIM is needed to unlock the phone. After phone is unlocked, remove the battery, insert SIM as desired and re-insert the battery. Phone MUST be restarted to use the new SIM card.
Go to Settings
Go to Options
Go to Advanced Options
Go to Sim Card
HOLD ALT and press: M E P 2 (Please note that you will NOT see what you type on the screen)
It will ask you for the unlock code. Enter it and then press trackball to confirm and your phone is unlocked!