The short answer is it isn't practical. Sorry, it sounds like an intriguing idea, but the technology doesn't work right.
Wiring would be very simple. The low beam headlights already have a low and high beam circuit. All that would be needed is the addition of two more wires running from the high beam circuit from the low beam lamps to the new dual filament high beam lamps.
But the only way I know of to get true low/high beam headlamps would be to switch all four bulbs to 7" lamps designed for a two headlamp vehicle. That would probably look pretty goofy, and would require fabrication of new mounts for the larger bulbs and modification to the grille.
