Well, I did it. There was a considerable amount of haze ion the inside of my headlamp assemblies, and it was driving me nuts. I read the instructions above and thought, "that's what I need to do!" So I ordered 3-something litres of absolute methanol from a local scientific supply place and took on the task.
WARNING: The WK2 HID headlamps contain a certain amount of electronics (I think that they are ballasts and the self-levelling apparatus) that are not easy to remove, and so I did this procedure with all of that still installed. Methanol is often used in electronics cleaning applications, so i think that this is reasonably safe, but I would caution you to (a) ensure that you are careful not to saturate the electronics, and (b) ensure that the assembly is very dry before you start the thing up. Also, METHANOL IS FLAMMABLE AND TOXIC. Be careful with it and as I said make sure that the inside of the headlamp assemblies are dry before you start up the lights.
To remove the headlamp assemblies, you have to remove (partially) the plastic fender flares, lower front fascia, the bumper fascia, the grill, and the fender close-out panels that sit atop the fender, just under the hood. The manual says that you should disconnect the battery cable too (HID is dangerous) That all took me about 90 minutes, because I went slowly and was a a bit apprehensive. With these items gone, it is a simple matter to remove the headlamp assemblies; it's just three screws that are easy to access. Because I didn't want to re-aim the headlamps when I reinstalled them, I put painter's tape around the outline of the plastic brackets that are part of the headlamp assembly to give me an index point for the reinstall.
After that I removed the wiring harnesses and the bulbs (careful around the HiD system) and placed the headlamp assemblies on a soft towel. I poured about 250ml of MeOH in the smallest bulb socked hole and swished it around inside for maybe 3 minutes. I used my finger to clean some heavy buildup on the DRL reflector above where the bulb would normally sit, then sloshed the MeOH around to wash that away.
i them propped each assembly up on end with the corner marker light down to let it drain. I propped a hair drier in position so that it would blow inside and left it there for maybe 45 minutes until the assembly was dry and warm to the touch (the heat will help the MeOH evaporate). I used this time to clean the bulbs with a microfiber cloth dampened with MeOH, and to spray down the black mesh grill insert with trim restoring goop.
i reinstalled and started 'er up. The internal haze is largely gone. It is well worth the time it took.