Since the iPod subject comes up fairly often and because I have upgraded my own installation in the NSX I have made a new step by step photo tutorial:
click here for the tutorial
The new tutorial uses the USA*Spec Aux Interface adapter in place of the FM modulator in the previous tutorial. The USA*Spec device is approximately $50-$60 at your local Circuit City store. There is more explanation of its features in the tutorial itself. Enjoy!
The audio quality through the interface is as good as the factory CD changer and there is capability for an additional input in the future (XM/Sirius, GPS, etc).
For those that want to use a wired FM modulator instead (as demonstrated in the old tutorial) here is the link:
click here for the old tutorial