This tip is on loan from a French site posted as: Alain27 - Easily adjust the headlights according to the load, which reads "Returning I suffered a lot of calls for lights, but set at night at the edge of the road is not obvious!
With Coke stoppers glued to the super-glue on the adjustment screws, we obtain a knob that can be adjusted while sitting on the machine.
No need to look at the screw, we find the "wheel" to the touch.
It is necessary that the cap is mounted tight without play on the head of screw, to the collage to apply flat with a screwdriver then let the glue dry several hours before use.". The pix
http://www.DL650.org/photos/pbsoluces/Alain27/bouchonphares.jpg, shows the coke bottle cap and screw setup.
Not sure if this will work on the later models but from the pix, it is does work on the gen 1 Wee.