How to import KML file, with custom data, to Postgres/PostGIS database?

you can use ST_GeomFromKML as this page.

SELECT ST_GeomFromKML('
        <LineString>
            <coordinates>-71.1663,42.2614 
                -71.1667,42.2616</coordinates>
        </LineString>');

or you can use ogr2ogr as following to process entire KML files;

ogr2ogr -f "PostgreSQL" PG:"host=yourhost user=youruser dbname=yourdb 
                            password=yourpass" inputfilename.kml

i hope it helps you...