using PostgreSQL

[Christian Eichert]

I am reading here in the Documentation:

    GnuCash by default stores data in an *xml* format. Starting with
    version 2.4, GnuCash financial data can be stored in a *SQL
    database* using *SQLite3*, *MySQL* or *PostgreSQL*.

But there is no further word spent about this important features.

Can Someone tell me how to enable the default storage in PostgreSQL format ?

regards
Christian