In SAV 10. It is not the SSC that downloads the definitions or updates the definitions on the clients. It is the SAV server that does this job SSC it only used as a console to manage policies and groups. for clients.
In SEP 11 everything is done by SEPM and not the SEP client on the server.
SO for manually updating definitions on the SAV 10.x server you need the XDB file.
Read this document for further details of the procedure
Updating virus definitions for Symantec AntiVirus Corporate Edition 10.x and Symantec Client Security 3.x
http://service1.symantec.com/SUPPORT/ent-security.nsf/docid/2005040711404048?Open