Cole Hersee sells different round wiper switches. I don't know if this will help you but maybe worth checking into.
http://www.elecdirect.com/media/specsheets/CHe1.pdf
Wish I had wiring diagrams for the switches but I can't find any. I know most of the big rig (18 wheeler/industrial truck) places here in town are the only ones that carry CH brand so maybe it's the same where you are at. Maybe they'll let you take a look at the wiring instructions.
Alex