You wont have that package inside the sepm.
the packages which are listed in sepm can only be expored
when you export it ,u uncheck single exe , save it and follow the above document to update the virus defs.
We then use the migration and deoployment wizard to push this package to clients.
Inside sepm you can add packages when they are new versions of sepm release
https://www-secure.symantec.com/connect/de/forums/install-packages-client-groups