All you need is a Michigan ORV sticker and a spark arrestor. You can get the former at most every bike shop in the state and some gas stations and Meijers' as well.
We've got several great trails up here, so if you're planning on coming check out
http://www.michigan.gov/dnr/0,1607,7...8330--,00.html and then decide how long you can take off work and where you'll end up camping
I'm trying to schedule the EBTR so that it doesn't get too close to a D14 hare scrambles or enduro, but those are usually good fun as well.