Portupgrade, how to disable dialog configuration?

[Pawel]

Hi
I have installed port eg. postfix already. All flags, that this port was 
configured with are in /var/db/ports/PORTNAME/options file.
Now I would like to upgrade this port via portupgrade.
My questions are:
Do I have to tell portupgrade to read this files if I simple want to have 
this port to be upgrade with the same flags,
and if so how can I do it?
How can I disable ports dialog configuration?

-- 
Marry Christmas and happy New Year,
Pawel