In Preferences > Tools > External Tools
Click the + button to add a new item. Enter these settings:
Program: /usr/bin/python
Parameters: -m SiteHTML "$ProjectFileDir$/"
Working directory: PATH TO SiteHTML*
You can then use the macro simply by selecting it in the Tools window menu.
If you want to use it in the toolbar, you can use the 
icon.
* This is only necessary if you do not use the python setup script