Did you go through all the Jungleflasher steps and save the images every time it asked you? If so you will have a copy of the origional firmware saved somewhere, with key included. If you are wanting to restore the origional firmware just load it into jungleflasher (1st tab I think, where you can spoof image) and then write firmware using mk32 tab. If you are wanting to put ixtreme onto the drive, load origional image in 1st tab, then load ixtreme as target firmware then click spoof (middle of page). That will loads the dvd key onto the modded firmware and then just write the firmware to the dvd.
If you don't have the origional firmware backed up or the dvd.key file saved you are screwed. This can be recovered from the NAND but involves a bit of soldering and knowledge of using NAND software to read / write. This is only possible on xbox's manufactured before June of this year and without the live update from August