To recreate the bug install install jre 1.4.2_09 and then follow the instructions at http://webeng.sfbay/internal/internal_release/javaclient_update_setup.html , but use the following url for the updateservlet field: http://latte.ireland/update/1.5.0/map-1.5.0.xml .

Once you have done this, then go to the control panel and go to the java plugin menu and click on update field and then click update now. Go through the installation and when you reach the offer screen only Google toolbar will be offered.
Just to make things clearer, this problem only affect Windows 98. Every other version of Windows offers GTB and GDS. Hence why I am pointing out the inconsistency of the installers behaviour.