I've finally got it working
It was a lot of effort sorting through bad instructions, zero tech support and misinformation on the web but it's all been worth it now.
You lucky people won't have to go through all the pain - I'll write up a how-to for you
For those with a 2009 (or very early 2010) 370Z with factory Nav see here for my reverse camera solution
For those with Premium Connect, read this post for info on a cheap reversing camera solution. Buy one here