French date

Hello,
Is there a simple way to configure the postgres server so that it always
understand the french date format 'dd/mm/yyyy' ?
Or is there a call i can perform in my client application that could
have the same effect ?

I wish i had not to set some easy forgetable environment variables such
as LC_TIME.

For instance in SQL Server i was able to issue a "set dateformat 'dmy'"
in the begining of all my transactions to get it done and that was fine
for me (and my customers...)

Many thank's in advance.