Initial stab at using the openstudio-aws-gem instead of the old aws.rb script, uncomment lines 529 and 530 to use the gem after installing it in the ruby-2.0.0-aws-win32 like so (note bundle does not seem to install gems to the correct location):

E:\openstudio-aws-gem>C:\working\openstudio\build\OpenStudioCore-prefix\src\OpenStudioCore-build\ruby-2.0.0-aws-win32\bin\gem install aws-sdk-core:2.0.0.rc14
E:\openstudio-aws-gem>C:\working\openstudio\build\OpenStudioCore-prefix\src\OpenStudioCore-build\ruby-2.0.0-aws-win32\bin\gem install semantic:1.3
E:\openstudio-aws-gem>C:\working\openstudio\build\OpenStudioCore-prefix\src\OpenStudioCore-build\ruby-2.0.0-aws-win32\bin\gem build openstudio-aws.gemspec
E:\openstudio-aws-gem>C:\working\openstudio\build\OpenStudioCore-prefix\src\OpenStudioCore-build\ruby-2.0.0-aws-win32\bin\gem install openstudio-aws-0.2.2.gem

You may also want to comment out line 1793 to preserve the private key file