Representing tonality via text

Note: this is adapted from elsewhere but it's more appropriate here.

You can use adverbs in the quotation. E.g.
(Mockingly) Why not?
"Why not?" [she said] mockingly.
WHOA  sounding surprised
"Really?" he says, pretending to be serious because he wants to steal her pocketbook while she's not looking, but she mistakes for cheap moves--and so she looks away, saying "I'm not that easy," only to look up again and find them both gone.
Why not? --he said laughing --I'm game.
Etc.
The last example is rather like in Polish; every change in speaker is presented with a dash, and quotations are offset with a helping phrase because it is spoken by a narrator (the "she said" part). (Note that it's not capitalized tho, so its not a new sentence.) It may not be easy to come up with words for every sense you're going for (tho there are lots of words in English," he said, being droll) but then you can make up words for those manners of speaking. The strikethrough is a way of making it seem more meta like for making comments in programming code; stuff that's written and crossed out is understandably not officially part of the text tho still there. You can present implied subtexts that way too, like how it would be if you spoke and intoned those words. It basically imitates the effect of speaking by sneaking in more, it doesn't necessarily give the reader a blow-by-blow of it. I like to italicize the text that is crossed out too.
E.g.
--I would hate love to have you over more often.
--I like that but I hate everything else.

What is weird, is that some languages e.g. Japanese present solipsistic speech (i.e. talking to oneself) in young children by talking in the 3rd person. It sounds kind of crazy to English people, like something a mad person might do. There's even a trope of characters using quotatives for their own speech, which definitely sounds dissociative. It's funny tho when that character is speaking in a monotone, and their narration adds how they intend to be heard, or hear themselves. [url=http://hasegawa.berkeley.edu/Papers/Soliloquy.pdf]Here's some more on soliloquy in Japanese.[/url]

"That's absurd," I murmur irritatedly to myself.<--Here the utterance is performed; tho it is kind of a lie if you don't say it too. Maybe "I write in anger" is more honest but it makes less sense. Both incidentally are performatives.
"Sarah thinks its crazy," says Sarah quietly to herself. Or "she says~" <--Japanese style example

Libreoffice gives you a ton of text formatting options e.g. Small capitals, double, triple lining etc. I like punctuation marks for beginning sentences too á la Spanish e.g. ¡ ¿Why do you ask?? You could always innovate new punctuation marks.

Maybe there's a history of using emoticons, comics, or ideograms of authors' feelings?

Diminutives, denigratives, honorifics, etc make attitudes more explicit. Certain sentence-final particles in Japanese serve only stylistic purposes. Of course there's an endless number of ways to change narration to capture speech. Otherwise you'll have to dig into intonation which is a big field. I'm digging into [i]English Intonation[/i] by Wells, but im using ad hoc labels for several things which aren't finely distinguished in the different methodologies. None are really super-comprehensive for what a native speaker knows about the language tho. For instance, 'disbelief' and 'incredulous' accents have very similar profiles (tho they are distinct; they have different  height spans and different onsets within their syllables); overall, you're better off just labeling them.

On the other hand, certain gradients that people are super aware of, are handy to have a notation for. For instance, "Tell me." Say the first word high and the 2nd one lower. There are several minute variations on it. If you pronounce "tell" gently rising, you'll sound urgent. If you keep it level, it will sound neutral, and if you pronounce "tell" sloping down, you'll sound confident maybe even reassuring. (That example is from Bolinger's [i]Intonation and Its Parts[/i], page 225. That general profile is considered an A-profile in his terms, with different "glides".) I still think its more convenient to use adverbs here, tho e.g. urgently, flatly or plainly, and confidently or reassuringly. I honestly think its a bit tedious labeling stuff with [url=http://blogjam.name/?p=9070]intonation diacritics[/url]. (Almost forgot to mention, but the American and British approaches have only been partially reconciled, that program uses a British accent. It should still be useful, but you may want to do some work.) Same reason I like audiobooks tho.