A Few Hook Questions

[eluser]CroNiX[/eluser]
It doesn't look like the global CI object is available to some hooks. If you look at /system/core/CodeIgniter.php, you will see exactly the order that CI loads things, and when it fires certain hooks. Not everything is fully loaded depending on what hook you are trying to access.

Again, the hooks documentation is very lacking, which is probably why hooks are rarely utilized.

Has your friend who suggested you start down this path actually tried to do this? You might ask him/her how they did it.