Some sort of ordinary 3 position (center off) SPDT toggle switch remains a viable backup. Here is Toyota's recommendation for how to remove the assembly:
Using an "L" shaped plastic trim tool, pry between the assembly and headliner along the edge nearest the windshield (I use a set purchased from Harbor Frieight -
http://www.harborfreight.com/4-piece...kit-95214.html ).
There are 2 blind retainer clips above the sunglass storage cavity that retain it to a bracket in the roof. Once the windsheld-end of the assembly is moved inward 1/4"-or-so, slide it toward the windshield and the other edge will release for removal.
Unplug the connectors.