If you follow the procedure below, you will easly JB & Install whatever you want.
1) Restore latest iOS from Itunes to your apple TV
2) Download RC6 of GreenPois0n from http://www.greenpois0n.com/
3) Connect your appleTV to USB cabel and power
4) Connect USB to your MacBook or Laptop
5) Start greenpois0n
6) Click Yes on screen with the message If you are jailbreaking an Apple TV
6) Bring AppleTV to DFU mode through
Press Menu & Down Buttons together until light quickly flashes
Release both buttons
Immediately Menu & Play/Pause buttons togerher until light quickly flashes
Now push Jailbreak button on greenpoison
7) On completion of the jailbreak process, click Complete! button
8) Wait for minimum 40 seconds before disconnecting USB cable until Greenpois0n finishes the jailbreak process on your Apple TV
9) Unplug USB cable, connect the device to your TV, navigate to “greenpois0n”, select “Inject Software” and install Cydia package.
10) After the installation is complete press MENU button to reboot.
11) nitoTV will appear instead of “greenpois0n” heading. You can now install third-party software and plugins, such as XBMC, Exposed, Overflow, BTStack, Weather, etc. (NitoTV->Install Software).
12) Update nitoTV under nitoTV options
13) Install XBMC from nitoTV software installation menus & openshh
14) reboot your appleTV from nitoTV menu
15) Download aTV Flash (black) Beta3 from your account at firecore.com
16) Run installation of aTV Flash
17) The installation will stop with "*** Installation Failed. Sorry, the installer could not install. Maintenance (Error 8.100)" Don't worry!!!!!
18) Login into yout apple TV with ssh root@XX.XX.XX.XX (IP-Adress of your AppleTV - Password is alpine)
19) run following command there
apt-get install --reinstall com.firecore.maintenance
21) reboot your AppleTV
22) Everything you want is there :-)
23) Install CouchSurfer etc. from maintenance menu :-)
I also connected appleTv to Dreambox via XBMC and whatch TV from AppleTV :-)