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