setting datestyle for different databases within a cluster

Boy, I'm just full of questions today ...

Is there a way to provide different persistent settings for DateStyle for
different databases within the same cluster?

Simply put, I've got two databases and I'd like to have 2 different DateStyles,
and I'd like to have it so I don't have to set the DateStyle at the beginning
of each session.  Looking through the docs:
1) I don't want to use SET DATESTYLE because I can't guarantee that each app
    that connects will set it since I can't control them all.
2) I can't use the postgresql.conf file, because that forces me to use the
    same DateStyle for each database within a cluster.
3) I can't use the environment variable for the same reason as #1, in addition
    to the fact that many of these apps may access through ODBC.
4) I tried, experimentally, to set DateStyle in the pg_settings table, but it
    seems to work some magic that the setting is set back to the config file
    default at the end of a session (bummer).

Any suggestions?

--
Bill Moran
Potential Technologies
http://www.potentialtech.com