How to use the routemap.util.customfields function in routemap

from django.contrib.gis.db import models
import routemap.util.customfields as cfields
from django.db import connection, transaction
from django.conf import settings

from osgende.tags import TagStore

class RouteTableModel(models.Model):
    """Generalized model for table with route information.
    """

    # only the fields required by the generalized functions
    # are added here
    id = cfields.BigIntegerField(primary_key=True)
    name = models.TextField(null=True)
    intnames = cfields.HStoreField()
    geom = models.GeometryField(srid=settings.DATABASES['default']['SRID'])

    def tags(self):
        if not hasattr(self,'_tags'):
            cursor = connection.cursor()
            cursor.execute("SELECT tags FROM relations WHERE id = %s", (self.id,))
            ret = cursor.fetchone()
            self._tags = TagStore(ret[0] if ret is not None else {})
        return self._tags

    def localize_name(self, locstrings):
        for locstring in locstrings:
            if locstring in self.intnames:
                if not self.name == self.intnames[locstring]:
                    self.origname = self.name
                    self.name = self.intnames[locstring]