I like the original, but I also really agree with Cindy's ideas... especially about not calling it a "role."
I also avoided labeling myself as anything (transsexual, transgender, etc.), but that's something of a personal obsession of mine, lol. I just told them what I was doing, and what to expect. I thought about mentioning it causing me emotional pain and all, but I feared it'd seem like I was fishing for sympathy... or like I was apologizing for it with, "I know this is weird, but it's OK to do because I was really in pain." I figured they really didn't need to know my personal emotional struggles, but just how it would affect them.
Since you have the support of management, it might be helpful to slip in a subtle hint about "management knows about this, and is cool with it." I'm not sure how to word it, but maybe get the point across that you have their cooperation?
~Kate~