Right..
So you need to sign the package with SignApk before applying the update. Other than that, it's a working OTA.
So, to recap: extract cache.img from the tar, unyaffs the img to get the zip and pass the zip through SignApk, apply as an OTA through the modified recovery, profit!
Remember to wipe your system after applying, the CSC update screws up your system pretty bad (it's the same as seen when upgrading from G-series to H-series)
And now to restore the backup and return to a CSC free life
