EKA code - perhaps dealer can provide that based on VIN if you provide enough proof of ownership. With the green alarm box sending a coded message to the ECU before start, you won't whip the electronics without spending more on equipment and learning than a used matching ECU & alarm box. If there was a MacGyver "jumper" mod it would be well spread across the internet by now.

 

The generic 1515 code seems to work for NAS vehicles. Here's a link to some other fixes, one involves disconnecting battery while key is in position 2, etc. Some things for RR and Disco work the same or close.

Security and Alarm System Operation & Diagnosis on Range Rover 4.0/4.6/P38A

 

Found this:
Discovery 1 EKA Code Online or Telephone 01379 669375.
It's a British site, apparently, and I have no idea how much "£16.67" is, but probably cheaper than having it towed to a dealership.

 

A dealer or someone with a scantool that has this ability can do this. The options on the alarm for immobilixation (or not) are pretty good.

I know the Hawkeye can do it, as I've used it to change my alarm option and program a new remote.

 

Real quick, because nobody mentioned it: you might have to pull the drive shaft to use the car dolly. I don't know if transfer case in neutral will be enough.

 

Thanks for the suggestions everyone, very helpful. I am thinking at this stage I will investigate purchasing a Hawkeye scanner, it looks like it could do the job of deimmobilizing