Flash MX 2004.
edge.splitEdge(t)
t A floating-point value between 0 and 1 that specifies where to split the edge. A value of 0 represents one end point and a value of 1represents the other. For example, passing a value of 0.5 splits the edge in the middle, which, for a line is exactly in the center. If the edge represents a curve, 0.5 represents the parametric middle of the curve.
Nothing.
Method; splits the edge into two pieces. You must call shape.beginEdit() before using this method.
The following example splits the specified edge in half:
var shape = fl.getDocumentDOM().selection[0];
shape.beginEdit()
shape.edges[0].splitEdge( 0.5 );
shape.endEdit()