I interrupt my challenge posts to bring you this tidbit.

Several months ago, I filled out a form at UNC's School of Information and Library Science site to get the director of their school librarian program to contact me.  She finally got back to me recently, and I was pleased by her response, though it didn't exactly tell me anything new. (Emphasis Added)

Dear Ms. H,

You sent information to our school library interest database some months
ago but the database was in the process of being revised and I am only now
getting to the point of responding.  I apologize for the long delay.

You inquired about what you need to NC certification as a school media
coordinator (the official name for the school librarian) through our
program.

The state requires for this 076 certification a a valid NC teaching
certificate (which you have), a master's degree in library science with
specialized school library courses (which you don't have although you have
some children's literature courses), fieldwork (which might be waived for
experience) and a passing score of the PRAXIS specialty area exam.

The details of what is required are spelled out in more detail on the
following website:
<http://sils.unc.edu/programs/continuing_ed/slmc/licensure.html>

You meet the teaching certificate requirement.  Latin and mythology is a
good background especially for a high school teacher.  You would need to
enroll in a master's program in library science and take courses in the
school library specialty area to qualify for licensure as a school
librarian.

Let me know if you have further questions and again, apologies for the long
delay in responding.

Co-Director, School Library Media Program