Django - Costum admin filter not by field

Question

Possible Duplicate:
Custom Filter in Django Admin

I have a model:

class MyModel(models.Model):
    ...
    @property
    def is_done(self):
        """ Returns True / False """
        ...

Can I create an admin filter that filters according to 'Is Done' with the options 'All', 'Yes', 'No'?

Thanks