All I had to do was create the user in the Publisher table...
I used the HSQL_Database_Manager to do execute the following statement:
INSERT INTO PUBLISHER (PUBLISHER_ID,PUBLISHER_NAME,EMAIL_ADDRESS,IS_ENABLED,IS_ADMIN) VALUES ('juddi','juddi','juddi@xxx','true','true');
I doubled checked to be sure the juddi.properties file had the user=juddi ,
and I can now update JUDDI running ontop of JBoss 4.0.2 from both UDDI4J and UDDIBrowser.
There are ddl scripts in the juddi-service.sar/META-INF directory that has data being populated into the DB when JBoss starts. So you should try to add users/delete users etc from these ddl files.
Apart from this, please read the wiki pages for JUDDI configuration.