Use this article to create NTP only package.though the size will of a full package but it will only install NTP when deployed on the client.
Creating custom Client Installation packages in the Symantec Endpoint Protection Manager Console
http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2007110513361348
However for all your clients in order to install NTP aswell.
go to admin- install packages upgrade groups with package- select the latest package-select the groups--upgrade settings--uncheck "maintain existing client install feature set" then scroll down and select all features.--next -finish
after some time all your clients will have NTP installed but you will have reboot the client inorder to enable NTP
Note: NTP will not be shown in SEP client interface until the client is rebooted.