What I know, is that European models use the brown wire for both the position (aka pilot) light and the taillight. On those European models you can also bring these lights on by switching the key to "P". On US models only the taillight will be on in "P" mode. In the "P" key position the instrument lights are supposed to remain off.
This is what I did, but you need a European headlamp reflector* for it: I replaced the 4 Watts Ba9s bulb by a 20 Watts halogen that I now use as my DRL. Saves 35-40 Watts. I'm still looking for a stylish switch to mount on the handlebar so I can switch the pilot light only without the taillight and instruments lights. When I need those, like on entering a tunnel, I can still switch the standard Honda RH handlebar to "P" and so add the instruments lights and taillight.
*I'd have an European headlight reflector suitable for H4 anyway (Cibié, Hella, Bosch, Marchal) and with the Philips X-treme Vision Moto H4 in it, you'll have the very best. On countryroads in the dark the UStype headlamp is next to useless .