I had the same Error 9.100. You have a successful jailbreak.
I got a successful installation after doing the following.
1. Repair disk permissions with disk utility , then restart. (not sure if needed, but just in case.)
2. Open iTunes and turn on home sharing. BUT DONT CLICK DONE. Leave that itunes homesharing window on. You can still switch between playlist.
3. Turn on you Apple TV and turn on home sharing in Apple TV. Now you should be able to see Computer.
4. Turn on Airplay, if not already on. No password
5. Install ATV Flash pkg.
6. Hopefully, you get a proper installation.
I am now having trouble with the plugins, Couch Surfer Pro only one to install. Installation problems with Media Player. Not sure about other plugins. Might have to ssh to install.
UPDATE : i have got all plugins installed successfully. 3rd party plugins - XBMC installation failed.