In the state of Michigan, all you have to do to become an officiant is to meet with your "church" and fill out their paperwork. This means you can just fill out
I spoke with Oakland county today, and they said that neither Michigan nor Oakland county require you to do any more than that. You need to sign the paperwork with your name and your "church" and submit the records to the county. You also need to keep a copy for yourself FOREVER as a record that the people are married.
And that's it. You can marry people. Crazy huh?
Please note: If you are getting married in another state, this may not apply because each state has it's own rules.