Originally Posted by
SSUte01
If the OS supports the IAC drivers of which some P59 and some don't, it should simply be a matter of changing ETC under the system options (System --> General --> System Options from 1 to 0 and then utilising the IAC tables that already exist. You certainly won't be able to Write Entire a P01 OS from a VY, that will fail or potentially corrupt your ECU if it even erases and attempts to write.
I don't know if Holden OS support IAC drivers. If your VZ doesn't, it should just be a matter of finding a P59 (i.e. 1MB ECU as per VZ LS1) OS that does. It may end up being from a US vehicle, but wouldn't surprise me if the Holden OS did support it. I have never tried to achieve that so I don't know.
Can you keep the ETC or is the intake on the conversion not going to allow it as if you have the pedal assembly you could keep ETC although I can understand why you would want to swap.