The only thing I used JB weld for the 2nd time around was to permanently glue the Range Rover shrouds (the shiny chrome cosmetic bits) to the projector assembly. As far as attaching the projector to the stock housing, there's no JB Weld. I did this intentionally so I'd be able to tweak the rotational alignment once I had the headlights bolted into the truck. That's where I goofed the first time. Now that I've had them on the truck for about a year, I can tell that the rotational alignment is starting to drift a little, but it's pretty insignificant and not enough to overcome my laziness/perfectionism.
The left-to-right alignment wasn't something I messed with. I don't think there's an easy way to adjust this. I wish there were because that way I could aim both the L and R units "cutoff" point to the exact same spot. In practice, it hasn't been a big deal. Maybe someone else has a solution for this.
You can adjust the vertical alignment fairly easily using the screws on the back of the headlamp housings. I started by using two cars w/ factory HID headlamps (see earlier posts in the thread), taking pictures of their output and then using those pics to align the new ones. You can also try putting masking tape on your garage wall to mark off the light coming from the stock bulbs. That should get you somewhat close.
One last observation: The cheap Chinese-made HID ballasts have two quirks about them:
1) They take several seconds to bring the bulbs up to full brightness. This is different compared to factory OEM systems where the bulbs are on full blast within 2 or 3 seconds.
2) They create EMI/RF interference that affects AM radio reception.
We get what we pay for....