I was discussing this issue with Steve W. in Philly (about one becoming an Announcer or MC at a Regional)... and I'd say the best route is to practice at off-seasons, then try to get signed-up as a trainee at a Regional. However typically, FIRST would like to keep the Announcing/MCing positions to the older crowd (same goes for judges, the people who look good on paper). So you'd have to be really good to climb up in the ranks.
In addition, something that could work just as well (after you've gotten practice), approach the committee of a newer Regional in your area who you know could use the help.
These are just some thoughts, I know I'd like to MC one day... there needs to be more energetic females out there on the field
ByE
erin
p.s. Just remember, sometimes the more you push... the more they push back. Let FIRST people know you're out there, keep practicing... and one day they'll approach you for help. Get to know the people running the events, because they typically won't request the help of people they don't know (or weren't refferred to by a friend).