Django Admin - Add extra dialogue on field

Question

I would like to have an extra layer of input security on a certain field in admin, very much like the password field:

class MyModel(models.Model):
    very_important_field = models.CharField()

So instead of showing the input form for very_important_field

There should be a link (as with password) that leads to it's own action (like /password) with an own form where you would have to type in this very_important_field twice.

• Could you please point me to some docs how to achieve that?

I do not need an explanation how to change the widget or how to write the proper form for this, just how to wire it in admin in a way that there is an extra action.