from django.contrib.auth.models import User

# Save the original method
old_set_password = User.set_password

def set_password(user, raw_password):
    if user.id == None:
        # It's a new user. We must save the django user account first.
        user.save()

    #
    # Do something with the user obejct and the given raw_password ;)
    #

    # Use the original method to set the django User password:
    old_set_password(user, raw_password)

# Replace the method
User.set_password = set_password