Since you mentioned Terminal, I assume you are using a Mac.
To get XBMC on your ATV2, you need to ssh into the ATV2. The command is
You should be asked for a password. It is alpine. A warning message should appear asking you to add the IP to your RSA account. Accept the warning.
Then, enter these commands in order:
apt-get install wget
wget -O- http://apt.awkwardtv.org/awkwardtv.pub | apt-key add -
echo "deb http://apt.awkwardtv.org/ stable main" > /etc/apt/sources.list.d/awkwardtv.list
echo "deb http://mirrors.xbmc.org/apt/atv2 ./" > /etc/apt/sources.list.d/xbmc.list
apt-get install org.xbmc.xbmc-atv2
You should then have the Eden build of XBMC on your ATV2