How can I use SST with IE on Windows?

In most of my use cases I use Ubuntu and SST works great. On Windows it runs well in Firefox, but when I use the -b InternetExplorer argument, it fails with the error listed below. I assumed this was because I was lacking a webdriver for ie, but from what I can tell I have one - in the C:\Python27\Lib\site-packages\selenium\webdriver\ie directory I see IEDriver.dll. Is there something more I need to do to make this work with IE?

Error:

Traceback (most recent call last):
  File "c:\python27\lib\site-packages\sst\runtests.py", line 250, in setUp
    webdriver_remote_url)
  File "c:\python27\lib\site-packages\sst\actions.py", line 176, in start
    browser = getattr(webdriver, browser_type)()
AttributeError: 'module' object has no attribute 'InternetExplorer'