I bought this Blaupunkt cable to connect my iPhone to the Alfa head unit.
You simply plug it into the CD changer port on the back and short Pins 13 &14 (e.g. using a bit of wire, paper clip etc), this will allow the headunit to recognise the input.
Also comes with the CD player removal tool.
Will work on pre 31/12/2003 models.
$15 posted.