First the connectors. These are the main problem as the dock has a male micro USB and a male micro HDMI connector, which were designed to plug into sockets on the appropriate Motorola smartphone. The earlier Pis didn't allow power to flow in via the USB A sockets, but the later ones like mine, do, and this makes things easier as you don't need to cut and solder any cables at all.
I found the following on Ebay:
- a micro USB extender cable which connected to the dock's male micro USB connector
- a female micro USB to male USB A adaptor, which connected the end of the micro USB extender cable to one of the Pi's USB A sockets
- a female micro HDMI to male mini HDMI adaptor
- a female mini HDMI to male HDMI adaptor
The first HDMI adaptor is quite chunky, so I had to remove some of it with a Dremel (other small grinding gadgets are available) to allow it to plug in cleanly without fouling the USB plug. The Pi is quite light, and the two HDMI adaptors can support it quite easily, but it is obviously fragile so care is needed.
The micro USB plug on the dock is strangely tight in the extension cable socket. The two ends of the cable can be plugged together easily, so I suspect something is up with the connector on the dock, and will be trying not to unplug the sockets attached to the dock if that can be avoided.
Once everything is plugged together, just open the lid to enable the power, and away you go! The two USB sockets on the back of the dock are recognised and Raspian auto-mounts USB sticks through them, so it's a good solution for backing up data from the SD card.
I think that the Atrix dock will be a boon for using, setting up, and backing up Pis as you don't need to worry about finding cables or spare keyboards.