Just posting my "took too long but finally finished it" project. Basically, I removed the factory pop-out cup holders from my 99 GTP and built an iPhone holder/dock in its place. I'm really happy with how it turned out actually. Took a lot of experimenting to get right, but it overall has a very clean look.
When it is closed, it looks completely stock, but it flips open to reveal a channel and a USB connector for the iPhone 4/5. The USB runs from the back of my radio, through the center console, up through the box inside the armrest and through to the base of the new box.
I always have trouble uploading pics here, so there is a link to an album of the console out of the car with my custom box in it below.
http://imgur.com/a/vdF6E
Let me know what you think!