jack the car up at the front wheel and working from inside the wheel arch, remove the plastic splash guard (there are screws all around the wheel arch) and you will see the antenna module in there.
You will need to disconnect the antenna connection from inside the car and pull it through also. You'll need to remove the passenger side kick panel and the cover under the glovebox to find this too.
A pain in the rear, but quite possible once you see where it all goes.
Thanks all. Just a quick tip (don't know where to put it) on the related head unit install.
I found that Repco sell a whole range of wiring harness converters (from AeroPro I think it was). I used an ISO to VR harness for $17 and it went, 'click' - 'click' and it was fully wired! :w00t:
Sorry if that's old news,, but it saved so much time and didn't need the colour codes I downloaded from another thread.