Python bindings in GnuCash portable

[david_lynch]

I am running GnuCash 2.6.3 portable on Windows Vista SP2.

I am trying to use python to input share prices (modifying 
http://wiki.gnucash.org/wiki/Stocks/get_prices ), because other methods 
don't work.

The list archives seem to indicate that python bindings for windows are 
problematic. However, the change log for GnuCash portable implies they 
are implemented.

I get the error message:

     from gnucash import Session, Account, Split
ImportError: No module named gnucash

How do I get the code
      from gnucash import Session, Account, Split
to work, please?

David Lynch