Definately the run up and board jump will be the key! I have a teeny weeny gymnast who has to handspring over 120cm in October - she is a good 10-12 cm shorter than this herself! However, although she isn't doing the vault on her own yet, she actually has the best first flight out of my whole group purely because she can run fast and jump hard (and actually seems to naturally understand the biomechanics of it all!) We are currently working on it on 110cm until everyone can do it!
It did take my weeny one ages to get her flatback vault though and I refused to move her onto handsprings until she could flatback properly.
Good Luck! With lots of practice, hard work, good coaching and determination she'll get there!