For those who have not been following Andrew Revill's work on MEMS and 5AS, he has published s/w and a relatively simple cable spec to programme a 5AS without removing the ROM.
andrewrevill.co.uk/MEMS3LucasImmobiliserSupported.htm
In addition to adding/changing the key fobs it also allows ECU pairing and other options. Using an old VW KKL cable and OBDII Y cable from the my hoard of stuff in the cupboard I had it working in a couple of hours.
Great work Andrew!
I can now complete my slow-burn project to replace the single connector 5AS with a later dual-connector version to flash the indicators on lock/unlock, finally install central locking and also install the fob energiser coil into the steering column cowling for automatic disabling the immobiliser. ("This occurs automatically whenever the key is inserted into the starter switch and turned to position II provided the handset is in close proximity to the switch.")
I have had this on the bench for a few years but had not means to change the MEMS pairing code.
