And it went quite well I thought.
I first came out to the CEO (A lady) and she accepted the news very well, asked intelligent questions, and gave me a hug afterward- wow, i've never seen her show affection toward anyone! She also seemed tickled to have another female on the engineering staff. Win #1, because if the CEO is happy everyone is happy.
I then visited HR and gave the HR lady a letter and she also took it well and was happy for me. Win #2.
Last, i came out to my boss. He was absolutely shocked and speechless. He apparently doesn't know anything about TG people and he had a hard time wrapping his head around the idea. He wasn't hostile or anything but I think he's going to reserve judgement. He is a good guy and a great boss and I think he'll come around.
So, 2 out of 3 ain't bad

I'm coming to work as Eva on Sep 17th.