Here is a link to the Wisconsin temporary smog exemption form:
http://www.dot.wisconsin.gov/drivers/forms/mv2472.pdf
On the form is a space for 'other'.
There is a telephone number to call for questions (608) 266-1466 for emission exemption information.
You could also email one of the three people with electric cars in Wisconsin on the EV album - they are probably the best source as they have 'been there, done that'.
http://www.evalbum.com/geo/Wisconsin