Mn laws don't protect you in wisconsin, but then again if they really wanted to fire you there are always ways. That said, If they value you, they should still value you after. My boss was more then a little worried about my transistion on the job, but really it was no big deal. Of course by the time everyone else knew, I had already made the complete transition to female clothing, makeup etc. Just did it small steps. It's been 4 months for me know and gee everyone is fine with me as me.
Be brave and be yourself. OK I was scared to death when I told my boss. Tough day, but it's all behine me now
Take care
Beni