The easiest solution would be to utilize a momentary ground switch, which could be as simple as a horn button or the like, that you just tap and it flips back and forth from hi to low beams. To do that, you would keep your regular headlight switch that has OFF-ON-ON but the the current would run through a VW Latching Relay that is flipped back and forth by the momentary ground switch. You can see my VW Latching Relay here:
Enabling Headlight "Flash to Pass" in 10 Minutes or Less and you can read about it and the use of a latching relay in detail here:
https://mgaguru.com/mgtech/accessories/at113a.htm One cool aspect of doing this is that the momentary ground switch would also act as a Flash-to-Pass whether the headlights are on or off. Just touch the momentary ground and you flash your high beams.
