I perform Ultimate Flashback all the time.
I usually perform the trick in conjunction with two other book tests, Insight and The Wizard's Manual, and it's a great 1-2-3 punch. Different effects with each book, and it gets gradually more amazing, with effects that go far beyond just divining the word.
By far the most powerful way to perform this trick is to borrow the books from a shill. This can be justified in some venues, such as a coffeehouse, a private home, or a library, where the audience might reasonably believe that the shill might be in possession of books. In other places, however, it's just not credible, as when performing at the Magic Castle and corporate banquets.
I start out with the riffle glimpse, which works quite well and hard to backtrack.
I skip over the alphabet sentence, although I've heard that some people swear by it. But with my style, where I just do two or three divinations per book at most, the alphabet divination would be unnecessary. Does anyone out there use the alphabet divination? Is it powerful in a unique way?
If you give volunteers a choice of which page to look at, they will invariably choose the left-hand page. When revealing "Mr. Brewster," I say that I'm getting a name, but that I can't quite see the first name. I reveal the last name, and then ask what the first name was, a bit distressed that I couldn't get it. When they say "Mister," I laugh it off, saying, "Well, of course, Mister!" That's a bit of a convincer.
The dictionary revelation is by far the most powerful of the revelations; don't forget it. You will tend to wear out the gaffed dictionary after a while, wearing a huge break on pages 104 and 183, and that may give away the method.
When that happens, just get a regular ungaffed dictionary and highlight the words "everything" and "lumberjack." There really doesn't need to be any justification for the words being highlighted; when they turn to that page, it's just weird. If the books aren't borrowed but just presented, you could say at the very beginning that you woke up last night and highlighted a word in the dictionary and don't know what significance that will have.
If the books are borrowed, you just tell them to turn to the page number you wrote down, and ask them if anything jumps out at them.