Aye it is, the original for this was part of the OCD mods done a few years ago by Jaxel, here's the link.
http://www.eq2interface.com/download...ledgeBook.html
I found the line you referenced, I got a thin line that shows up and works, tweaking it still to see if I can get an actual button to show.
[edit]
got it fixed =) here is the fixed file if anyone is interested. Will post as an update to the OCD Knowledge book.