The libraries needed are: xlutils, xlrd and xlwt. They are all under the package called xlutils. So just issue the following command.

sudo pip install xlutils

To verify:

localhost:~ birdchan$ python
Python 2.7.2 (default, Jun 16 2012, 12:38:40) 
[GCC 4.2.1 Compatible Apple Clang 4.0 (tags/Apple/clang-418.0.60)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import xlutils
>>> 

Should have no error messages.