JDBC - large objects

I am having some problem getting the jdbc driver to work properly with
large objects using standard jdbc interfaces.  The tables are pretty much
standard relational tables except for one column that I serialize 
implementations of the java.security.acl.Acl as objects into. 

The error I get is: ERROR:  lo_write: invalid large obj descriptor (0)

This was the same error I got running the blobtest until I applied Tatsuo Ishii's
patch I found in the mailing list archives. I tried the same thing in my code
(turn on explicit transactions when storing a blob) but it doesn't seem to
have any effect.

I have tried defining the acl field in my create table statement as both:
:    :acl    oid,:    :

and
:    :acl    char[]:    :

And see same thing.

The same (java) code runs fine using Oracle 8 and their thin driver. 

I guess what I need to know is: is what I am trying to do possible using
PostgreSQL/JDBC without using the PostgreSQL extensions? (not an
option for me).  If so, what should I use for serialized columns in the
create table sql statement?  Can it be done without turning off autocommit?

Thanks in advance for any help anyone can provide.

Cordially,

rc

ps: My environment is:
Solaris 2.7 (intel)jdk 1.2 (jdk 1.1 fares no better)PostgreSQL 6.5