Hello,
for implementing SSO for SNC you can use Secure Login.
Please take a look at http://scn.sap.com/community/sso
Depending of the authentication method you want to use here are some links with videos:
http://scn.sap.com/docs/DOC-40178
http://scn.sap.com/docs/DOC-40179
best regards
Alexander Gimbel