To ssh root into your atv2 find out the IP of from your network setting on apple tv 2
1: ssh email@example.com
You will then see this
The authenticity of host '192.168.1.101 (192.168.1.101)' can't be established.
RSA key fingerprint is f4:81:56:ac:ae:ec:4a:60:a4:6a:ca:09:83:6d:4f:39.
2: Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.1.101' (RSA) to the list of known hosts.
3: Enter the password firstname.lastname@example.org's password: =