Flash MX 2004.
text.orientation
Property; a string that specifies the orientation of the text field. Acceptable values are "horizontal", "vertical left to right", and "vertical right to left".
This property works only with static text; it generates a warning if used with other text types.
The following example sets the orientation property to vertical right to left:
fl.getDocumentDOM().selection[0].orientation = "vertical right to left";