Hello
There are 2 solutions:
there is the solution with SAP Logon Tickets. This solution is included in SAP Netweaver.
http://help.sap.com/saphelp_nw70ehp3/helpdata/en/4c/5bd4fe97817512e10000000a42189b/content.htm
So this is a solution for SSO for NWBC but you also want to have a Kerberos integration ... this is an issues because only SAP NW Java is suppporting SPNego and not SAP NW ABAP. So this solution is only working if the first request will be send to SAP NW Java server and the user gets then a SAP Logon Ticket. See also:
Furthermore there is the additional product SAP NetWeaver Single Sing-On available which support also NWBC 3.0 and higher: http://help.sap.com/nwsso10 -> installation -> components: secure login client + secure login sever + secure login library. NWBC is supported here via certificates out of the box.
You can find also a how to guide here for SAP NW SSO:
http://scn.sap.com/docs/DOC-29687
See below blogs
NWBC meets Single Sign-On: Simplify Secure Data Access (Part 1)
NWBC meets Single Sign-On: Simplify Secure Data Access in Remote Scenarios (Part 2)
Part 3 - NWBC Authentication & Single-Sign-On (SSO)
Regards
Vijay Kalluri