If all you machine can communicate and update from the SEPM then the easiest way is to update your SEPM via JDB file and then it will distribute from there. Download the JDB files from the interent and then import them into the SEPM which will update and then distribute them to the clients.
http://www.symantec.com/business/support/index?page=content&id=TECH102607
Below are the links for the JDB files to download to update Sonar and IPS
http://www.symantec.com/security_response/definitions/download/detail.jsp?gid=sonar
http://www.symantec.com/security_response/definitions/download/detail.jsp?gid=ips