did this once and after a restore all i have to do is re-upload the lockdown directory to the phone..
1. copy the whole Lockdown directory from /private/var/root/Library/Lockdown
onto your pc
2. Copy the deleonju files into the Lockdown folder on your pc
3. Open the new data_ark.plist file, and copy the entire <data> tag just after <key>-DeviceCertificate</key> onto the clipboard
4. Open EACH .plist file in the pair_records folder, and paste over the device certificate data tag
5. Open the .plist file in the activation_records folder, and paste the <data> tag over the (probably empty) <data> tag after <key>-DeviceCertificate</key> - note that this device certificate key is further down the file than in the pair_record .plist files
6. Copy the new Lockdown folder contents into /private/var/root/Library/Lockdown
7. Reboot the iPhone and enjoy!