transaction isolationa level - SERIALIZABLE

Hi list,

I have some problems with SERIALIZABLE isolation level, namely my users are
plagued with concurrency errors. As of postgres 9.1 (which I'm running)
there has been a change to SERIALIZABLE logic, unfortunately my application
has not been updated to work with the new logic. I don't have an access to
it's code and the only thing I can do is to report the issue to the
authors. But before I do it, since I don't actually need SERIALIZABLE for
my use, is it possible to have transactions always run in default READ
COMMITTED mode, regardless of application level SET SESSION CHARACTERISTICS
AS TRANSACTION command ... ? (like e.g in postgres 8.1 where SERIALIZABLE =
READ COMMITED)

regards
mk