The AUX-IN adapter works well, as long as you dont mind not being able to control the IPOD from the HU or steering wheel. If your not bothered, then this is the cheapest solution. Also, you'll not get a line lvl out signal, so you'll be faffing around with the volume level on the ipod every time you plug it in.
as for the wire, do some googling or look on audiworld forums, i seem to remember that this needed connecting to a switched 12v+ as this was to detect when the auxilliary device was switched on. IIRC people just connected this straight to the +12v for the automatic antenna (if u have a feed from the HU), that is switched on/off with the HU. I could of course be way off here though, so check /ubbthreads/images/graemlins/smile.gif