There is no direct airside access between T4 and T5. That said, there is a very roundabout way to do it, assuming that the American Eagle folks are not checking boarding passes...you can take the shuttle from T4 to the AE satellite terminal, which is out past T8. From there, you can take another AE shuttle to T6. T6 is connected airside to T5. I would allow 30 - 45 min, depending on how often/fast the AE shuttles arrive. However, if the AE folks are checking at T4, they may not let her board the shuttle. Last time I was at the AE satellite terminal, no one was checking boarding passes there.