Here are some pics of my custom mounted dock to hold my iPhone. I basically just built a sturdy platform out of wood and secured it the same way you secure the box that usually fills the empty DIN. Tricky part was getting the platform to be level, as the head unit and mounting bracket are angled upward slightly. The dock charges the iPhone (or any iPod you put in it) and connects to the aux-in of the head unit for music. Unfortunately the iPhone does not output phone call audio through the dock connector, but I still achieve hands-free calling via a bluetooth headset which I store discretely in the driver-side door handle crevasse.
All that's left is to make a piece to fit over the opening around the dock painted the same color as the plastic in the dash so it blends.