I have 4500K headlights and 300K fogs.
Do the following:
1. Buy some NON-PERMANENT Epoxy (make sure around 1200-2000psi max bond pressure)
2. Remove radiator cover and look down untill you stop the metal bar of the inner bumper assembly.
3. There is a HUGE indentation which can comfortably fit slim HID ballasts (buy SLIM HID kid if possible) and most likely enough for regular ballasts.
4. Mix your epoxy wait a few minutes till it gets less runny more sticky and smear A LOT on the bottom of each ballast CAREFULLY lower the ballast into the indentation in the bumper assembly bar and press it down FIRMLY for 2-4min (if you have quick set epoxy).
5. Route all wires as necessary.
6. Re-mount radiator cover.
This way they are hidden and well protected from the elements. Check on the epoxy periodically (every 6months or so) to make sure its holding OK, if it is then you should be good. Its been fine for 2 years on mine now. Good Luck!