Without a projector retrofit or a reflector designed for the intended bulb... beam pattern is really hit or miss...
If it sprays light all over the place you just end up looking like "that guy" on the freeway just blinding everyone in both directions.
That said, I did experiment with an HID kit in the stock fog housing which is a projector type design intended for a halogen bulb, and it really doesn't look half bad, but its still no where as nice as it should be when you compare it to an OEM type setup.
Regardless of the route you take... chances are it wont be DOT approved so it wont be road legal. But if you can make that beam pattern look correct, and aim the lights correctly, most people can get away with it just fine.