Depending on where you are, that law is very conceived by everyone. I'm in the UK and a lot of people think that, but what the MOT guidelines actually say is that self levellers and washers on Xenon applications must work to pass an MOT.
It does not say they need to be present. They just have to work
if you have them.
I contacted VOSA themselves on this and they came back confirming that self levelling and washing devices don't need to be present for a Xenon headlight to be legal. However, the Xenon light must be E marked and, when buying aftermarket, that's very hard to come by.
When going for an MOT though, that's irrelevant. As long as the beam pattern, light output and colour is good (no blue lights and no blurry beam pattern), it'll pass.
But like I said I'm not sure if you're in the UK or if the laws are the same, but if it states that levellers and washers must work on xenon lamps, that doesn't mean you need them - it just means they need to work if you have them.
ANYWAY! Back on subject, as this is something I'd like to do too as it's just plain cool to have
let me know how you get on!