This tutorial will guide you that how to jailbreak Apple TV with Seas0nPass jailbreak tool, which can create custom firmware like PwnageTool.
Download and install iTunes 10.1.1 (check for updates through Software Update located in Apple menu).
A micro USB cable.
Jailbreak Apple TV 2G with Seas0nPass
Unzip Seas0nPass.zip file and launch Seas0nPass.
If your AppleTV is not yet jailbroken, select ‘Create IPSW’. (if already jailbroken, and you just need to do a ‘tethered boot’ scroll down).
It will automatically download the latest Apple TV software which will be used to create a custom jailbroken software file.
When prompted, connect your Apple TV using a micro-USB cable (leave power disconnected), and hold both the MENU and PLAY/PAUSE buttons for 7 seven seconds.
iTunes will open automatically and start the restore process.
Once the process will complete, you will have jailbroken Apple TV.
Tethered Boot with Seas0nPass
Launch Seas0nPass and choose the option Boot Tethered.
When it will ask connect the Apple TV to your computer through USB. Wait for the rapid flashing light then connect the power. Once both are connected hold MENU and PLAY/PAUSE buttons for 7 seven seconds.
Seas0nPass will automatically complete the tethered boot process. Once complete, remove the USB cable and connect the HDMI cable.