Some photos taken through the build process:

From the Back:

Just in case you were wondering what the back of one of these monitors looked like here's a piccie. Really interesting, eh? If you observe carefully you'll see three cables on the right proving this shot was taken post-mods:

The dangling cable is the power chord for the laptop PSU emerging from an extra slot Dremmeled in the back of the case, and the black cable bent next to it brings USB from the laptop motherboard out through a widened hole in the metal shielding to the input for the monitor's USB hub. You may just about see the same trick used to bring HDMI from the computer to the monitor input - in this case a custom cable I made up, but any short and flat cable would do.

From the Back... again?

First off you get a good grip of the plastic cover, now missing in this picture, and give it a good pull up and out. It should then just unclip and slide off. Next remove the four revealed screws that attach the monitor stand.
The tricky bit comes next, be really careful - you don't want to damage the TFT pannel or mess up the front bezel of the monitor.
Grab a flat-head screwdriver (wide and thin for perference) and with your fingers pry up the inside of one of the short sides of the bezel in the middle with your fingers only! That should reveal a small gap in to which you can insert the screwdriver - between the plastic and metal underneath NOT between the metal and the TFT! Push in the screwdriver horizontally to the far edge under the bezel and give it a twist. (don't lever!!!) You should feel a catch pop open. Repeat the same trick top and bottom on the same side, followed by the same for the two long edges, and finally the remaining short side.

Where to put that Motherboard?

From here carefully flip the whole thing on to it's face once more and the plastic back pannel should just lift off, being careful to detach the small PCB's for the power switch and controls as you go. There are four screws (at each corner) attaching the metal shielding to the TFT, remove these and that should just lift off. Again BE CAREFUL; there are a number of plugs you will need to detach round the edges as you go and finally the TFT connector itself once you can reach.

The photo shows where I intended to mount the laptop motherboard, having checked there would be room! Also a careful look top-right reveals my 'mounting system' for the WiFi board. The white flat-cable South of the motherboard goes to an LED board that I later found wasn't needed for any useful function. The silver power plug (South-West) ended up facing North.

Final Positioning:

In the end I included the battery as there was room, and why not? Everything is securely attached to the back of the TFT with strips of adhesive Velcro. Easy to use and reposition, while being non conductive and not too thick to stop things fitting in the limited space.
The fan was the tricky bit for a couple of reasons. It's got two potential exhausts, one through the heatsink fins and one through the opposite side from the intake. The fan needs to be mounted (velcro again) in such a way that the potenital exhaust opposite the intake is blocked without snagging the blades of the fan while making sure the side-exhaust through the fins butts up nice and closely. This is all part of the shell of the HP Ultrabook and needs a resonable approximation for the conversion. Also the wires for the fan are amazingly delicate, so you don't want to fiddle too much!

The TFT Driver Boards:

Shown here is the inside of of the metal shielding that mounts the two driver boards for the TFT. A power board to convert mains to the neded voltages and a driver board for the USB hub and VGA/HDMI/Audio functions.
I gave this step a good deal of thought before comming to a final solution. On the one hand I wanted something that preserved as much of the monitor's functionality as I could while making as few external changes as possible, but at the same time make the build as simple as possible for me and anyone who might copy it.
To this end the the only changes to the metal shielding were to cut off the top side for easier access...

HDMI and USB Cables:

...and widen the holes the USB and HDMI inputs went through so I could run cables from these to the laptop ports. I could have soldered these cables to the inside of the connectors for greater neatness but wiring up an HDMI connector or very fiddly and this way I'm reminded not to use said ports if the computer is powered up. Equally I could have wired up an adaptor to connect the laptop's TFT port direct to the monitor's TFT but that would have gained me nothing but extra complication for the loss of a useful VGA input and force me to wire the audio seperately. The cables can be seen poking out of the bottom of the driver board on the left; a black USB cable and a custom HDMI cable I had laying about from a previous project.
I intended to mount the laptop PSU in the gap above the TFT driver board and wire it's mains inputs directly to the mains input for the TFT power board so keeping just one power lead...

Fully assembled:

...but I felt this could be literal over-kill for what was meant to be an easy project. Oh, and trying it only produced flames.
As soon as I realised the standard PSU would fit as seen in the photo to the left with the aid of some more Velcro and the screws intended to mount the speaker (remounted with more Velcro) I cut a slot for the extra power cable in the back pannel and called it a day. Once installed I used a cable-tie to hold the power cable in place so it couldn't be pulled out once the whole thing was back together.
Finally I used a screwdriver to short pins and so find the power pins for the monitor and laptop power switch PCB's. Having found them I just wired said pins between both boards so the monitor's power switch would work for both it and the laptop PCB. Not perfect, but it's simple and it works.

The Ports:

From left to right we have the power port for the monitor, audio jack, pass-through for the HDMI, VGA-in, pass-through for the USB hub, and the power cable for the laptop PCB.
All functional, fairly discrete, easy enough to do, and a useful reminder not to accidentally use the HDMI or USB hub ports without unpluggling first!

Once the monitor stand is back in palce it's fairly stock-looking, even to the extent that the monitor stand has cable clips on both sides suggesting that two power cables was how it was always meant to be be.

The Finished Product:

I bought a very nice Logitech wireless USB keyboard and mouse to match the finish of the monitor and plugged their dongle in to the 'spare' laptop motherboard USB port that was otherwise offending me by being both redundant and inaccessible. I may replace this in time with another USB hub but as this machine has a full set of wireless connectivity and two USB ports via the monitor's own hub I may not. I may also fit the laptop webcam, but as I've yet to find a use for such devices I probably won't bother. ;-)