# in userprofile/models.py
class Profile(models.Model):
    user = models.ForeignKey(User, unique=True)
    location = models.CharField(max_length=100, blank=True)

# in settings.py
AUTH_PROFILE_MODULE = 'userprofile.Profile'

# in backend/default/__init__.py
def register(self, request, **kwargs):
    username, email, password = kwargs['email'], kwargs['email'], kwargs['password1']
    if Site._meta.installed:
        site = Site.objects.get_current()
    else:
        site = RequestSite(request)
    new_user = RegistrationProfile.objects.create_inactive_user(username, email, password, site)
    signals.user_registered.send(sender=self.__class__,
                                 user=new_user,
                                 request=request)

    # how to add 'location = USA' to profile via signals here?

    return new_user

LOCATION = 'USA'

# in backend/default/__init__.py
def register(self, request, **kwargs):

    username, email, password = kwargs['email'], kwargs['email'], kwargs['password1']
    if Site._meta.installed:
        site = Site.objects.get_current()
    else:
        site = RequestSite(request)
    import settings
    if settings.LOCATION:
        location = settings.LOCATION
    new_user = RegistrationProfile.objects.create_inactive_user(username, location, email, password, site)
    signals.user_registered.send(sender=self.__class__,
                                 user=new_user,
                                 request=request)


    return new_user