Disabling login via Heimdal

[Robert Fitzpatrick <robert@webtent.com>]

I installed the Heimdal-0.6 port under FreeBSD 5.2.1 and it seems to
have enabled kerberos login for pam or something? When ever I restart a
service that runs as a non-priv user, it prompts me to their kerberos
login. For instance, if I restart amavis which runs as the 'vscan' user,
it will prompt for the vscan@EXAMPLE.COM password. I am not ready to
start using this as I have not setup Heimdal the way I want, yet, and
cannot seem to find where to disable this for now. Can someone tell me
where to look? Also, when I'm ready to enable this, do I just setup a
service principal for that service to avoid the password prompt?

-- 
Robert