My question is fairly straight forward: can you have more than one LoginHook or more than one LogoutHook?
I've done my own research and it looks like every time you add a new LoginHook, the previous one goes away. I think I can confirm this by running the old:
sudo defaults write com.apple.loginwindow LoginHook /path/to/script
Then checking to see that the loginhook is registered in the /var/root/Library/Preferences/com.apple.loginwindow.plist, then repeat the process by adding another loginhook, looking at the root loginwindow plist to see that the second script was over written by the first. There is never more than one.
Is that correct? Are you ever only able to have one LoginHook?