Hello,
The communications used when accessing the SEPM's web console are encrypted. This traffic is encrypted using the SEPM's own self-signed certificate (and therefore untrusted by your machines by default), which is the reason behind the certificate warnings you receive.
You don't need to do anything to add SSL encryption for console access, it is already there.
However, check these Articles:
Configuring SSL between Symantec Endpoint Protection Manager and the clients
http://www.symantec.com/docs/HOWTO55351
Symantec Endpoint Protection 12.1: Enabling SSL Between the Manager and Clients
http://www.symantec.com/docs/TECH162326
Enabling SSL Between the Symantec Endpoint Protection Manager and Client
https://www-secure.symantec.com/connect/articles/enabling-ssl-between-symantec-endpoint-protection-manager-and-client
Moreover, incase you are thinking using the SEPM 12.1 webconsole over SSL, check this Thread:
https://www-secure.symantec.com/connect/forums/how-install-proper-ssl-certificate-sepm-server
Hope that helps!!