h4s are generally for sealed beam designs or high/low dual fil bulbs. If your plan is to use an h4 bulb as a low and then use both for your high....why?
If thats wyour plan, you could just buy an h4 plug at any autoparts store, splice into the highbeam wire for the third prong and be done with it.
All this is assuming you already have a way to fit the h4 bulb, as no one makes an h4 conversion for the ellipsoid or US spec lights that I'm aware of.
<span style='color:gray'><span style='font-family:Courier'>1995 e36 3 Series RIP
1999 e46 3 Series BURN IN HELL
2000 MR-S Roadster= Current</span></span>