You planning to deploy the 12.1 packages using SCCM? Have a look at the threads below:
https://www-secure.symantec.com/connect/forums/deploying-sep-121-using-sccm-2007-r3
https://www-secure.symantec.com/connect/forums/sep-deploy-through-sccm
https://www-secure.symantec.com/connect/forums/sep-installation-sccm-task-sequence#comment-3699931
...from the SEPM level you can export either .exe install packages or .msi.