On the lighter side, I've always tied them to the backstop and had the team throw balls at her. After the first dozen balls, it doesn't hurt anymore.
Really though, try tennis balls first. Then work up to softballs. It appears that at one time, this catcher got hit in the face with a ball (not while playing catcher). You've got to get her to trust her mask and equipment. Tennis balls are soft and she knows that they will not hurt her. After she gets comfortable with tennis balls, make the move to regular softballs.