Alright, here's my two bits.
On my car I installed the STi projectors. They are *not* HID... just projectors with seperate low and high beam bulbs as opposed to the stock two stage bulb. For these lights, there is a way to make a PnP harness, but the problem with it is that when you turn on the highs, the lows turn off. This is how 99% of the people w/ STi projector wire them, which is a shame because that's not how they're designed. So, what I did for my car, was to grab a hand full of relays to build myself a circuit that allows the lows to remain on when the highs are switched on. The circuit really only requires one relay per light, however I wanted to be able to use higher wattage bulbes so I have an additional 2 relays per light so they can be wired directly to the battery with heavier gauge wire.
All that said, I don't think the work I've done is all that related to installing the stock HIDs. From what I've gathered, HIDs require a ballast and an ignitor. Basically, even though HID use much less power than hallogen bulbs, they need a very high voltage, which is what the ballast is for (much like fluorescent lights). The ignitor is for getting them to turn on. Much like my projectors, the HIDs will require seperate power for low and high beams, and I believe the low beam HIDs stay on then the high beams are triggered. Because this is *not* how the stock wiring works, you will need to build a harness like mine, more than likely. What I don't know is how the HIDs themselves are wired. If you simply need to supply power to the HID ballast to get them to turn on then my wiring diagram will apply, but if there's additional wiring for triggering the ignitor, or something, then we'll have to figure it out. Bring the light to the meet tonight and we can take a look at it.
Another more thing that makes these lights a little more difficult to wire, at least on the non-HIDs, is that they're
negitively switched. i.e. the bulbs always have power, and the grounds are switched on/off. There are issues when you start to use relays in place of bulbs... for example, the LED for the foglight switch is actually powered by the left headlight highbeam, when the high beam's are off... what this means is that if you have the fogs on, then turn on the high beams, when you turn the highs off, the relay for the high stays triggered by the current from the LED and the left high beam stays lit.
I had to rewire that LED to get it to work properly on my car.
Then there's the whole DRL issue... you probably shouldn't attempt to run the HIDs as DRLs. The power to the headlights for DRL use is stepped down from normal power.... that probably wouldn't be an issue if you use relays like me, but it means you'll be running around with HIDs on full all the time.
The leveling switch is another chore. If you've got the same one as me (6-pin) it's not so bad, but if you've got the 4-pin version like Tyson then we'll have to figure it out. Actually I think Tyson did all the research for getting the 4-pin switch to work, but we just haven't gotten around to doing the install. Perhaps after the 4th sometime we should have a headlight install meet, and take care of all this wiring!
I'll try to find my wiring diagram for my projectors... it might help you out a little.