I've downloaded source code for JDBC driver in order to output warnings during development phase of my application (so I can catch triggers messages at client side of the application).
This is the only change I've made (System.out... in addWarning methods - there is two: one for connection, one for statement).
Nevertheless, I has been obligated to change "alter database xxx set bytea_output='escaped'" in order to work.
In our production databases we have this option set to "hex", and works fine - is just with 9.2 DEV 1002 sources.