Scaleform displays a scrolling text box.

BeginScaleformMovieMethod(scaleform, "SET_MESSAGE")
PushScaleformMovieMethodParameterString("THIS_IS_A_LONG_MESSAGE_TO_SEE_WHAT_HAPPENS!") -- the message to display
EndScaleformMovieMethod()

BeginScaleformMovieMethod(scaleform, "SET_COLOUR")
PushScaleformMovieMethodParameterInt(6) -- the message color
EndScaleformMovieMethod()