Stay away from the Dice Module...I unfortunately bought it. I had it all of two day's before it stopped working. I called Dice Electronics and they were nice enough to send me an "updated" version... I've had the updated one in my car for about two weeks and it stopped working once. The way to get it to work again is to unplug the Dice unit and let it reset itself. I also bought the Dice vehicle mount along with a Pro-Fit accessory mount, those two items work like a dream. It's a pretty simple solution to hooking up my Iphone without having to use the ash tray and allowing it to be visible while i'm driving.
what you could do is get the Spec-Dock module and the Dice Ipod/Iphone mount that has the Ipod USB Adapter in the back and hook that up together and it'll work pretty good. The Spec-Dock has a Ipod power cable that runs out of it and will plug directly in the back of the Dice Mount. It's what I would have done if I hadn't already bought the Dice Module.
edit--I'm pretty sure that the Spec-Dock has an Ipod cable that would hook up to the back of the Dice Mount. I googled some pics and it looked like the same cable that runs out of my Dice unit.