If you want to flash on the bench, you will need to disable immobilizer. PRJ has repeatedly said that flashing earlier cars via obd doesn't work so well, so I would assume you can't flash via OBD (at least reliably). Make a backup of the eeprom, then disable the immobilizer, flash your file, and finally flash the original eeprom data back to the ecu, thus preserving your immobilizer functions. (I'd wait until the tune was dialed in first, that way you don't have to disable the immo before every write).
On another note, I'd love it if you could get me the .bin from your cluster. The software required to do so is in a sticky entitled "Bench flash s4 gauges with vag com" or something similar in the immobilizer/cluster section. If you get a chance, post it (and the matching eeprom) in the cluster dumps section!
cluster file and eeprom are posted in the cluster dumps.