There's a program called CSUtil that can be used to import users, groups, etc as detailed here:
http://www.cisco.com/univercd/cc/td/doc/product/access/acs_soft/csacs4nt/csnt24/csnt24ug/apimport.htm
In addition to this, you can import NAS's by using the format:
ONLINE
ADD_NAS:router1:IP:10.31.1.51:KEY:cisco:VENDOR:CISCO_T+
ADD_NAS:router2:IP:10.31.1.52:KEY:cisco:VENDOR:CISCO_R
where router1 and router2 are the names of the NAS, the key is "cisco" for both, and router1 is a TACACS host and router2 is a Radius host.
Hope that helps.