You can pass options to calibre_postinstall to disable any stage of the process.
Code:
Usage: calibre_postinstall [options]
Options:
-h, --help show this help message and exit
--use-destdir If set, respect the environment variable DESTDIR when
installing files
--do-not-reload-udev-hal
If set, do not try to reload udev rules and HAL FDI
files
--group-file=GROUP_FILE
File from which to read group information. Default:
/etc/group
--dont-check-root If set, do not check if we are root.
--make-errors-fatal If set die on errors.