The theory is there, however when I tried this previously (with a Nissan key) the companies I approached wouldn't program a key not supplied by them. Does anybody have someone that will do the work?
My theory is that you don't need someone else to register the new key with your immobiliser, there is a sequence using the brown master key to add new keys to the immobiliser:
1st switch on with the master key to MAR and then off, remove master key and place away from the ignition switch
Then program the new and old keys one by one by using each to switch on/off
(within 10 seconds)
But, I guess only if the new key has some sort of code in it, if its a virgin key, then I don't know if the above will work