No idea about their use in Lammies or the specific models you linked to. Someone on here has shown one though.
Wot I know comes from fitting to the car and trying to fit to the bike.
HID's are designed for use in a projector. Using one in a reflector gives the uncontrolled and unfocused output Tony described. Dazzlingly bright to oncoming traffic, but poor illumination of the road.
The various sorts of H4 fit can be a bit unpredictable as the lightsource is rarely where the reflector needs it to be. When I spent a lot of time looking at this for the bike, all the various H4 bulbs got a lot of flak for poor reliability and little output "on the road".
There are small(er) projector kits about now, sometimes even with a shutter to give a built in hi/lo beam pattern but they tend to be a bit long.
http://www.ebay.com/itm/2-5-Inch-Motorc ... 1289787356
The retrofit ones in my car only cost £25 a pair, but are massive at nearly 6" long. The smaller ones I've seen are maybe an inch, inch n' a bit shorter? You can maybe scale off the drawing on the ebay site.
The various LED lamps are coming along in leaps and bounds. Several companies have developed H4 fittings, but again the output is a bit uncontrolled compared to a whole LED lamp unit and nothing like as much light down the road. They need a dedicated reflector system to function correctly.
http://www.theonlinepartsshop.co.uk/sin ... ug-n-play/ As you can see, a bit spendy still. Would there be space for the fan unit behind the lamp?
Some cars are now coming with LED spot/fog lamps whether one of these could be sourced and made to fit?