There is currently no way to enable SSL connections with a PostgreSQL connection on tableau's 8.2 version for Mac OSX. It used to be that you could create a generic ODBC and turn SSL as described here: http://kb.tableausoftware.com/articles/howto/connect-to-postgresql-using-ssl-on-non-standard-port
Now there is no ODBC connections and PostgreSQL only has the following options:
Has anyone solved this problem with the Mac Tableau version with Heroku Postgres?
In order to connect via SSL, you can use the Tableau data extract API. Read the info you need and create a Tableau extract. Then you can connect to the extract via a mac, and rerun your program on a schedule to refresh the extract periodically. You may even see a nice performance improvement, at the expense of not reading live up to the minute updates.
Once Tableau improves their PostgreSQL driver to support SSL from macs, then you can replace the extract connection with a live one.