You have to install the RSA ACE Client (either for UNIX or Windows) on the CiscoACS server. I only have this configured on a Windows 2000 server so I can only provide you the steps for that.
1) Download the RSA ACE client from http://www.rsa.com
2) Copy the "sdconf.rec" file from your RSA SecureID server to the c:\winnt\system32 directory
3) Install the client on the CiscoACS server (during the install, you will be asked for the location of your sdconf.rec file, which is in c:\winnt\system32)
4) Make sure you have a valid user ID/token to test with and test connectivity using the "test connectivity" application after install.
5) In CiscoACS go to External User Database -> Database Configuration -> RSA SecureID Token Server -> Configure -> (you should see the "sdconf.rec" file on your ACS server now...the configuration is complete).
You can now configure users/groups to user SecureID as an authentication. Let me know if this helps!
