How to call a static methods on a django model class during a south migration

I'm writing a data migration in south to fix some denormalized data I screwed up in earlier code. The way to figure out the right value for the incorrect field is to call a static method on the django model class. The code looks like this:

class Account(models.Model):
    name = models.CharField()

    @staticmethod
    def lookup_by_name(name):
        # There's actually more to it than this
        return Account.objects.get(name=name)

class Record(models.Model):
    account_name = models.CharField()
    acct = models.ForeignKey('Account')

...

class Migration(DataMigration):

    def forwards(self, orm):
        # Fixing Records with the wrong FK to Account
        for record in orm.Record.objects.all():
            record.acct = orm.Account.lookup_by_name(record.account_name)
            record.save()

But this fails with

AttributeError: type object 'Account' has no attribute 'lookup_by_name'

I'm guessing south just doesn't support @staticmethods on model classes?

Trying to import Account directly fails, unless I also import Record directly and completely ignore the ORM object. Is that a safe option, since it's a data migration and the schema isn't changing? Or should I just run this fix by hand rather than in the context of a south migration.