Hello,
In reference to the Installation Procedure of Symantec Installation Manager, check this Article below:
Overview of the installation process
http://www.symantec.com/docs/HOWTO44330
Secondly, To get all your clients start reporting / communicating to the Latest Symantec Endpoint Protection Manager, you would require SylinkReplacer version_12.1.
To get that SylinkReplacer version_12.1 tool you will have to call symantec or log a web case.
QuickStart Guide - Create and Manage Support Cases in SymWISE
http://www.symantec.com/docs/HOWTO31132
How to update a support case and upload diagnostic files with MySupport
http://www.symantec.com/docs/TECH71023
OR
Regional Support Telephone Numbers:
United States: https://support.broadcom.com (407-357-7600 from outside the United States)
Australia: 1300 365510 (+61 2 8220 7111 from outside Australia)
United Kingdom: +44 (0) 870 606 6000
Additional contact numbers: http://www.symantec.com/business/support/contact_techsupp_static.jsp
Hope that helps!!