Is it possible to configure an IOS 12.2 device to authenticate with my RADIUS server instead of TACACS+? I don't have TACACS+ so I've been using just the local logins. I haven't been able to find documentation that indicates this ability.
Yes you can use RADIUS instead of TACACS+.
Here are the basics for the commands to authenticate to a radius server at the following address 22.214.171.124 with a backup server of local routers user database.
aaa authentication login default group radius local
radius-server host 126.96.36.199 key CISCO1