so far i done my e90 halogen to lci xenon ahl .
first you need to do is get the adaptive headlights and the footwell module (FRM AHL).you can go to ebay,there's a lot..
you have to rewires.add wires from FRM to headlights
it is a big different between halogen and xenon. so you'll buy some connecter and wires.
after rewires all the wires,you can turn on the car to check if everything works.
at this moment you'll see the error and the windows control malfunctioning,,so you need to code you car.after coding everything works OEM..
My modification method is based on the original BMW.everything OME.If there are any parts damage computer will prompt you..