Step#2: Use your desktop manager and backup your
8330's data.
Step#3: Go to the general settings on your
8330 and wipe it (be patient this operation may take up to an hour or more).
Step#4: Once the wipe is complete go to my computer and select the local c disk, go to program files, common files, then research in motion then select app loader, once your in the app loader delete the vendor file, it will be in xml format. The reason it is imprtant to delete the vendor file is because you downloaded the os from a different carrier and the vendor file acts as a copyright.
Step#5: Plug in your phone if it's not already connected. Now you will need to select the loader which is in the same place where you found the vendor file. The app loader wizard will guide through the installation, be patient, the loader will restart your phone.
Step#6: Once your phone is restarted the phone might go to the app updater if so update the apps that need to be updated. After that is complete go to the desktop manager and restore your phones data.
Step#7: Go to safety removal hardware then stop the usb mass storage. Enjoy!
Also, Xliderider has some great tutorials on here to help people upgrade to another OS.
A few things you need to mention are backing up 3rd party apps before wiping; there are two other programs for wiping, including BBSAK and JL_Cmdr; and use Shrink A OS to shrink down version 5 or on a Curve you will have no memory left when finished.
Or as the person above me suggested, use a Nathanix hybrid which I believe has already shrunk the OS.
