I have looked into this and contacted many people, none of which were very helpful - from emails to in person at the SOS. Online there is mention of a 3 Wheeler Basic Riding Course or 3WBRC in a few places but no information on where this class is available.
http://www.michigan.gov/sos/0,4670,7-127-1627_46351_46352-288975--,00.html
3-Wheel Basic RiderCourse (3WBRC) is the best place for motorcyclists to learn about riding a three-wheel motorcycle. The course includes four hours of classroom activities and up to eight hours of on-cycle riding exercises. A written knowledge test and a skills test are required to pass the course. Successful completion will allow students to waive the Secretary of State skills test and may qualify them for an insurance discount. Students must provide their own three-wheel motorcycle and proof of insurance. The motorcycle must be properly titled and registered, display a valid license plate and pass a safety inspection.
The best info that I got was when I went to the SOS, they gave me the booklet to study and a list of all the places by county that offer courses. This list differs from the one offered online. I found a place near Lansing that is a Bring Your Own Bike place, church parking lot, 20 min and $35. All the other places that I looked into were minimal $50 and 14+ hours of classes relating to two wheeled junk.
http://mrrsdrivingschool.com/road-test/Motorcycle Road Tests
Mr. R's has a motorcycle test site in Grand Ledge, located at:
Liberty Church
12745 Georgia St.
Grand Ledge, MI 48837
Appointments are made by calling the examiner directly
call Torey at 517-290-7368
convenient times
Cost of test $35
Motorcycle must be provided by applicant
Test takes approximatly 15-20 minutes