How to find the writing in/on the FEZ Tome artifact

There is one room in particular that provides what you're looking for. You don't need to copy NPC dialog, though part of the fun is copying the other wall-writings for later consideration. So there is no single intended method (I imagine most people will look online)—your method could work, though it sounds frustrating.

Want a hint for that room's location?

It's off of the waterfall room.

Want an even bigger hint?

A pillar in the room links the code to an English pangram (sentence containing every letter of the alphabet).

And to give it away:

In the tree room above the waterfall, a fox jumps over a dog next to this pillar, which reads all the way around: "The quick brown fox jumps over the lazy dog." (image)

FROM OUT OF NOWHERE 
IMPOSSIBLE VISITORS 
OUR BENEFACTORS

WATCHING OVER US 
IN THE HIDDEN FOLDS OF SPACE 
IN FRONT OF BEHIND 

GIVE THE GOLDEN GIFT 
A DEEP REVELATION 
OUR EYES WIDE OPEN 

SHAPES TO TESSELLATE 
WITH SACRED GEOMETRY 
AN EMPIRE TO BUILD 

A NEW PERSPECTIVE 
THINGS UNSEENS BUT ALWAYS THERE 
A NEW DIRECTION 

THE HEXAHEDRON 
THE SIXTY FOUR BIT NAME OF GOD 
THE POINT OF ORIGIN 

A PATTERN A CODE 
A DEEP UNDERSTANDING 
A GATE TO THE STARS 

ALL OF TIME AND SPACE 
AND THE SPACE OUTSIDE OF SPACE 
WHERE DOES IT END

The tome consists of haikus. Some were spread throughout the game—written on walls and repeated by owls. The book is read three-dimensionally, using a letter from each page in this order: 15263748. The text isn't rotated, and the translation starts in the upper-right corner and moves downwards. The decyphering technique is described at GameFAQs.