Try this one:http://www.cisco.com/en/US/docs/ios/12_2/security/command/reference/srftacs.html#wp1017941

I think I can get half of your request done, but maybe someone else has a better idea.It’s a very simple, but not an "automated subnet-based process" for enabling users to choose the TACACS+ Server where to be authenticated/authorized from.tacacs-ser...

ACS v4.2.0.124 90-Days Evaluation Softwareeval-ACS-4.2.0.124-SW.zipRelease Date: 11/MAR/2008Size: 55304.38 KB (56631684 bytes)http://download-sj.cisco.com/swc/esd/04/281458142/contract/eval-ACS-4.2.0.124-SW.zipHTH,