then download the Postgresqlsql ODBC driver http://gbord.postgresql.org and install it then make two strings one in wich there is the Oracle DSn , one to the new hosting Pgsql DSN , then both tools above permits synchronisation.
About frunctions and triggers paste them direcly to text files then go and insert them agian in the databse.
If you're under Linux you can do the same game with UnixODBC and pgadmin (both run on top linux or *nix)
or you can just down and use both sql plus and plpsql to pipe outputs of oracle in the inputs of psql, you cn rely in sed and awk in those technics.
The best practice evr is to get the dump of the database (structure and date) and to release it in pgsql , the sysntax is nearly the same if not the triggers and functions !
Finally, Openoffice for win/linux - supports natively Postgresql, through a DBA extension that you'll find ion openoffice site, and ODBC databse - offers an other way of migration of data and structures ; functions and triggers must be done separately as said above !