Thanks for the link, Solid. On this occasion I'll pass on that because I'm in the UK I don't want to pay through the nose for shipping. Instead, today I went out on a limb and made my own cover. Using the stock bulb holders I basically sawed off the rear of the holder, pulled out all the connectors, and fed through the xenon wires and finally creating a seal with the grommet that is attached. I then plugged the bulb holder into the rear of the housing.
Think I did a really good job if I say so myself and I'm impressed that an idea that popped in to my head panned out pretty much without hindrance!