Since 'methods' is converted to a set in the next line, there is no need for lists. Instead, use | and delete the conversion.
  methods = vars(Pack).keys() + vars(Grid).keys() + vars(Place).keys()
  methods = set(methods).difference(text_meths)
becomes
  methods = vars(Pack).keys() | vars(Grid).keys() | vars(Place).keys()
  methods = methods.difference(text_meths)

Now I am a little puzzled why this does not fail (3.2b1, winxp):
>>> from tkinter.scrolledtext import ScrolledText
>>> s = ScrolledText()
>>> s
<tkinter.scrolledtext.ScrolledText object at 0x00F6CF70>

On the other hand, this fails elsewhere:
>>> from tkinter.scrolledtext import example
>>> example()
Traceback (most recent call last):
  File "<pyshell#34>", line 1, in <module>
    example()
  File "C:\Programs\Python32\lib\tkinter\scrolledtext.py", line 49, in example
    stext.insert(END, __main__.__doc__)
  File "C:\Programs\Python32\lib\tkinter\__init__.py", line 2970, in insert
    self.tk.call((self._w, 'insert', index, chars) + args)
_tkinter.TclError: wrong # args: should be ".16421456.16190896 insert index chars ?tagList chars tagList ...?"