DialUpLoginManager loginManager = new DialUpLoginManager( con, moduleId );

Login login = loginManager.getLoginById( 123 );
Map<String, List<String[]>> attributeMap = loginManager.loadAVPPairs( login );

List<String[]> list = attributeMap.get( "default" );
if( list == null ) { list = new ArrayList<String[]>(); attributeMap.put( "default", list ); }
list.add( new String[]{ "mpd-rule", "xxxxxxxx" } );

List<String[]> attributes = new ArrayList<String[]>();
for( Map.Entry<String, List<String[]> e : attributeMap.entrySet() )
{
  String realm = e.getKey();
  for( String[] avp : e.getValue() )
  {
     attributes.add( new String[] { realm, avp[0], avp[1] } );
  }
}

loginManager.updateAttributes( login.getId(), attributes );

attributes.add( new String[] { realm, avp[0], avp[1] } );