The AppleTV seems to ship with no firewall rules configured. There is no need to hack up a way to disable the firewall.
In MacOS X, at boot time,
/usr/libexec/FirewallToolruns, which reads the file
Neither the binary nor the plist are distributed with the AppleTV OS, and it is therefore not surprising that in a default OS install, the ipfw kext has a single 'allow any' default rule:
-bash-2.05b$ sudo ipfw list 65535 allow ip from any to any
Enabling the Firewall
It is likely that copying over FirewallTool from an Intel Mac will enable MacOS firewall configuration at boot time. In addition, it is neccesary to create /Library/Preferences/com.apple.sharing.firewall.plist. If the prefs plist file does not exist, FirewallTool will not configure ipfw. There are several ways to create this file: