I'd like to say that Social Thoughts is spot-on.
If I had such a child, I'd say that the surgical option would not be available on my watch. My child would need to reach the age of majority first. Then he or she would have my emotional support for that decision, if that big step is what he or she truly wanted. (SRS is not the only option.)
In the interim, I would be agreeable to legally changing his or her name to an androgynous one, like Chris.
If and only if he or she requested it, counseling by a COMPETENT mental health professional would also be appropriate -- assuming that I could find one.
Dressing in a way that's appropriate to his or her gender of choice would also be OK. In order to avoid extreme, and possibly life-threatening bullying by his or her peers at a public school, I'd give serious consideration to home schooling.
If we went with the home schooling option, it would be desirable to find wholesome opportunities for peer socialization within a tolerant social environment. Toward that end, I'd also give serious consideration to joining the Unitarian Universalist Church.