Is this an older install?
You /should/ have a package called lmce-install-scripts, which replaces pluto-install-scripts. See if
apt-get install lmce-core lmce-install-scripts
provides a solution.
If you *must* just have a working install, modify /var/lib/dpkg/info/lmce-core.postinst and put
Configure_NTP_Server || :
in line 99.
But I would appreciate, if you first tried the apt-get.