Resolution:
Patches for GridServer version 4.0 and 4.1 and 4.2 can be uninstalled in two steps (4 steps, if using alternate base directories) :

   1. Restore all directory hierarchies from $DSHOME/webapps/livecluster/WEB-INF/uninstall/PATCHNAME to $DSHOME/ webapps/livecluster.
   2. Remove the file $DSHOME/webapps/livecluster/WEB-INF/config/update.PATCHNAME.properties.
   3. Restore all directory hierarchies from $DS_BASEDIR/WEB_INF/uninstall/RELEASE to $DS_BASEDIR/
   4. Remove the file $DS_BASEDIR/WEB-INF/config/update.PATCHNAME.properties.

Note : RELEASE for 4.2 is as following: R4_2_0_xx

For instance, to uninstall the patch contained in GridServer-4_0-Patch-20050220.jar (assuming standard base directories) you could use the shell script:

cd $DSHOME/webapps/livecluster
(cd WEB-INF/uninstall/4_0-Patch-20050220; find . | cpio -pdumv ../../..)
rm config/update.4_0-Patch-20050220.properties