If you bored of the claustrophobic environment of the your Marketplace on the Lumia device and want to install side load apps, a complete procedure allows you to unlock this privilege to bring out the best from the Nokia Lumia.
9. Create an account and include the "as a student" selection. Select the university or school and wait till 24 hours after verification.
10. Choose a location and select the closest possible to your current location.
11. Fill out the rest of the form. Then verify or confirm the email you have received.
After this process, the AppHub account has been created and will give your Live ID recognition on the phone you desire to unlock.
Process to Unlock:
1. Connect the Lumia device you want to unlock to the computer. You must have a Zune suite running and Lumia screen must be unlocked.
2. Open the "Windows Phone Developer Registration." It is a part of the SDK package you have installed earlier.
3. Enter your Live ID & Password that you used on the AppHub and then register.
And that finishes the unlocking the Lumia, sideload apps are now allowed to be installed. Visit the Developer's site about other details concerning the unlock procedure.