Basically, italic and bold are a crutch, which the Antiphonale cannot afford to provide, and assumes you will be proficient enough to get along without. That's how the monks do it, after all.

Accents above vowels are to let you know, when it is a word of more than two syllables, which one gets the word accent; so that you say "Dóminus" rather than "Domínus".

For the last part of your question, let's look at Sunday Vespers, say, the third antiphon. Above the initial letter it gives you two bits of info: 3. Ant., which is just labeling it as the third antiphon, and IV. g, which tells you which psalm tone you will use. In this case, it is the tone for mode 4, with the ending g. Now, remember, you are assumed to be proficient in chant; you would therefore be able to remember easily how the mode 4 tone begins. However, since there are a good many more endings, it wants to remind you of that; thus it gives you the E u o u a e for a reminder.

So, what to do?

Check out the Liber Usualis, which is a book aimed at parish choirs, and thus for many of the hours that you are likely to sing, it does indeed provide the italics and bold. You'll find Sunday Vespers on p. 250.

However, say you want to be able to apply italics and bold yourself.

The paradigms for the psalm tones are on p. 113 of the Liber. They show the tone laid out in notation, but they also describe the cadences, like so (here's the beginning of what they say about mode 4):

Mediant of 1 accent with a 2 preparatory syllables.

The "Mediant" means the middle cadence. When pointing, the "1 accent" is done in bold and the "2 preparatory syllables" are done in italic. Refer back to Sunday Vespers in the Liber to see how this works.

So, hopefully this explains how the Liber Usualis arrived at the following for the first verse of the 3rd psalm of Sunday Vespers:

Beatus vir qui timet Dóminum : *

(The first accented syllable before the asterisk gets the bold, and the two syllables directly before that get the italics.)

Hope this helps.

I would think, at any rate, that with examination of some of the many pointed psalms in the Liber coupled with a look at those paradigms you ought to be able to figure it out.

Also, I might add, that for pointing by hand (e.g. with a pencil), a logical substitute for the italics/bold would be something like the following, where the vertical line indicates the start of the preparatory syllables:

Beatus vir qui | timet Dóminum : *

Vale in Domino,
Jonathan

Thank you everyone!

I do know the tones well, but I'm wondering if other people come to sing the Chants with me - let's assume they know the tones for now - are you saying that we will just naturally sing the same notes? I didn't realise it was as simple as that!

I'm one who learned it from a book. The best source for me was the Antiphonale Monasticum I (2005), pages 509-528.

I agree, I really think it is necessary. I called it a crutch above but that gives the impression that it is a bad thing that should be done away with, and I don’t think it is. The Monastery local to me uses pointed texts.