Hi wildheart -
The wig-wag switch is linked to FSX's logo-light circuit.
I'm guessing you'd like a link to a desktop hardware switch?
The XML variable for logo-light is (A:LIGHT LOGO,bool).
If I recall, FSUIPC will be able to link to this by name or by its XML variable.
As well, you could assign a keyboard shortcut to logo-light using FSX's key assignments....then link to the shortcut.
Hope this helps.