Known values for blending modes are (From LuminicBox):

  MovieClip.BlendModeType.NORMAL
  MovieClip.BlendModeType.HARDLIGHT
  MovieClip.BlendModeType.OVERLAY
  MovieClip.BlendModeType.ALPHA
  MovieClip.BlendModeType.INVERT
  MovieClip.BlendModeType.SUBTRACT
  MovieClip.BlendModeType.ADD
  MovieClip.BlendModeType.DIFFERENCE
  MovieClip.BlendModeType.DARKEN
  MovieClip.BlendModeType.LIGHTEN
  MovieClip.BlendModeType.SCREEN
  MovieClip.BlendModeType.MULTIPLY
  MovieClip.BlendModeType.LAYER