Nothing beyond the built-in capabilities of Linux/Android to flash partition images from a Terminal with SuperUser permissions for 4.2.2. I think I told you about the flashable zips of just the 5.0.2 bootloaders for 35A and 36B I have in my ROM thread in my signature.
You could conceivably set up a script to use with the GScript app in the Play Store to downgrade to 4.2.2 - I just haven't felt like going to even that small effort.
Additionally, since the thread with the 4.2.2 bootloader isn't obvious given its thread title (which I never remember), I have a 7-Zip of the 4.2.2 bootloader along with a text file inside the archive with copy/pasteable text for use either in a Terminal with SU permissions, or via adb. The former is the easiest IMHO since the second requires a PC, drivers, USB cable, adb, a reliable connection, remember to give adb permissions the first time on the phone, and then superuser permissions again on the phone. Not a huge deal but at least as easy to just do it from the device itself.
I use 7-Zip archives for things that aren't a flashable zip, so it's obvious you can't flash it. X-Plore File Manager, ZArchiver and other Play Store apps will open them. I find in X-Plore that I must long-press the text file with the command(s) and choose to edit the file in order to correctly copy and then be able to paste the text into Terminal - don't know if that's a result of the Terminal I'm using or what the deal is.
The 4.2.2 7-Zip is in my Android File Host section which I link to in my ROM thread in my sig below.
We should additionally at this very late stage stop posting this VK810 stuff in the V500 thread.
Sorry to anyone else for any confusion.