Re: alfadiag interface
you need to buy a KKL 409.1 Interface, many of them on ebay.... either Rs232 or USB comm's
assuming the interface has a Pin 3 [ airbag ecu ] then you'll need to either modify the interface so as the wire from pin 7 [engine ecu ] is connected to pin 3 either via a 2 way switch or just solder straight across.
alternatively, if the interface doesn;t have a pin 3 then remove the panel of the car & pop out the diagostic socket.
use a paper clip to bridge across from 7 to 3.
afaik by doing this there is no issue or conflicts as each ecu communicates on there own addressing & baud rate.
a member here rarebear has 2 modified cables for sale , pm him