Get AptBackup. Now backup for Jailbreak apps in that, and sync with iTunes. this will make a backup of your phone. Restore your phone to factory, then upgrade to 2.2.1. Then use PwnageTool/QuickPwn/WinPwn to jailbreak. Now restore your iTunes backup onto the phone. finally, re-install AptBackup via Cydia, click restore, and all your JB apps will return as if by magic.