I too will have research this headlight off business, shouldn't be too hard
Its easy.
1. Loosen top screw in headlight shell and take off the front part.
2.Unplug the H4 and parking light and put aside the front part safely.
3.The H4 plug has 3 circuits. The green / white circuit is what we want.This is the low beam circuit. Cut away the black tape about a inch or so behind the H4 plug.
4.Now you have 3 wires... cut the green/white back from the H4 plug about an inch.
5.You will need about two lengths of auto wire ...and a on/off switch with led light to mount on the handlebar (22mm)...available from ebay,large selection.
6.Either solder or use male/female crimp plugs...join the two auto wires to the two cut wires .I soldered and used heat shrink to insulate.
7.Wrap the wires in black insulation tape ...then run the loom through the back off the headlight up to the handlebar to where the switch is to be mounted.
8.Connect the two auto wires to the new on/off switch.
9.Recheck all ok.
The high beam stays as normal...all you need to do now is use the new switch for on/off for low beam when required.
Aussie 650