Finally got done with my HID/Angel Eye install this weekend. Didn't get a chance to re-install the housings into the LS yet, and the car is filthy so I'm not going to take pics until she's cleaned up.
However, I did say that I would report today on whether or not a halogen housing could be used for HID's. The answer to that is "yes," but does require a little modification. It's also assuming that you are going to be and are capable of cutting open a headlight assembly (or know someone that can do it for you). Alax7's video and pics are pretty much all you need to get it done.
First off, the main reflector bowl needs to be swapped (one of the obvious things) - just requires some needle-nose or other pliers to squeeze the 3 plastic retaining posts to where the bowl mounts will slip past them.
Second, the high/low beam wiring harness needs to be swapped - including the external connector that connects to the car's harness. Once you have the plastic connector out of the HID housing, I recommend cutting/grinding/sanding the LOWER tab off of it before you put onto the halogen housing. It's easier to do, and once you connect the internal wiring harness, you cannot pull it back off so you'll end up having to deal with the whole housing at that point. The turn signal reflector bowl and harness can be left alone - they are identical between both housings.
Third, you'll need to cut an opening in the bottom of the halogen housing to allow the wiring harness from the ballast to go into the housing assembly. NOTE - I'd recommend this being the first thing you do after gutting the halogen housing. This is also pretty obvious when you have both housings side-by-side (or you'll see it pretty quick when you try to mount the HID ballast. I used a dremel and made the opening just slightly smaller than what was in the OEM HID housing.
That's pretty much it - definitely works so if you have a problem with your HID housing, just get a halogen assembly and use the guts from your HID. You'll have an easier time than trying to find another HID assembly.