Thanks a lot for your reply... I tried doing this and it didnt work.. Moreover, we need to add local aaa group for the firewall to prompt username/password during telnet session... I have done those and it still goes to usermode only.
Also, if you authenticate the username/password from MS AD using ACS server, how can we give privilege 15 to that particular user.
It is my understanding that what you are trying to do on the ASA is not possible. Atleast, that is my experience with ASA and 7.0 code. I tried this in the lab long time ago, when ASA and 7.0 was released.
I would be interested to take a look at your configuration/setup, in case you tweak something and get this working.