in recent versions of postgres, there is a "replication" mode designed
specifically for replication software to disable FK's and other
triggers. Perhaps investigate that.
the other option is to make your FK's deferrable, and do all your
delete in one big transaction with the FK checks deferred. not sure
if that will help.
either that, or order your deletes and loads in a way such that the
FKs remain satisfied. unless you have circular dependencies, this
should be possible.