Re: Alfa Keys (again)
If you can get the key code from an Alfa dealer (they charge for the code) then a key can be coded to your ECU, it shouldnt matter if it is a 2nd hand key but you would need the blade cut to suit your ignition, these are available from ebay sometimes but advanced-keys.co.uk may be able to get one.
If you cant get a code from Alfa then there are other options such as having the immobilliser function removed from the ECU (means it has to be removed and sent away for a few days) so that you dont need a transponder key to start the car, also there are specialist lock smiths out there (i know of one in Guildford, Surrey) who can re code your control unit, the one near me charges almost as much as the main dealer though!!
Hope this helps, if you can get a code then the rest is easy, I can code keys from my diagnostic kit and lots of garages are getting key coding upgrades to their diagnostic kit these days.