Now that we can install full Mac OS X on the Apple TV, it really opens up the doors for making softmods to the Apple TV.

It appears the full version of Mac OS X will boot from an external USB drive, according to Turbo, the hacker who first managed to get the Apple TV to boot from USB.

Once booted, you can modify the Apple TV’s internal harddrive without needing to crack the case; and so you could enable SSH, Apache, or Apple Remote Desktop. You could even install 3rd party media centers, or just install some plugins.

Booting from USB requires booting the Apple TV as nromal then holding ‘menu’ and ‘-’ keys on the remote to initiate a restore boot. From there it takes a bit of timing, Turbo explains, “If I hold down menu and - from poweron until the first screen flash, I believe that it does the equivalent of cmd-opt-p-r. I only got it to boot from USB by releasing it at that point, then hitting it again just before the screen flashes on the second reset.”

He went on to explain that after the initial boot in this fashion; the Apple TV now boots from his USB drive by default if it is attached.

Obviously, we expect to see a whole host of softmods crop up, allowing people to tinker with their Apple TV’s without having to void the warranty by cracking it open.

Update: Turbo has posted detailed instructions on this on his site