Basically your notebook script needs several functions that are currently distributed between several scripts as far as I know.
1) you need a console script that enables full text input - by default Ace has only limited keyboard support.
2) you'll need some sort of journal script that creates the pages(screens) where the player can write something
3) you'll need a script modification that combines the first two scripts and saves any changes to the notebook's pages into the savegame.
There should be one console script and a few journaling scripts on the master script list, but most probably you'll have to request someone to make you the third part - I don't remember seing that anywhere on the master script list or here in the forum.