Guestbook pagination2 users found helpful
Did you ever find a way to achieve this? I'm trying to do the same thing...
conversely the discussions add-on has a guestbook type UI in it, and it gives you a lot of other options you might find nice including pagination and sorting/filtering,etc.
Just upload in the blocks/guestbook/ folder and rename to .php
Around line 230 you can change the maximum results.