Like when you get irritated and say "tch" for example. I'm looking to do this in a 3rd person narrative context.
As they are regular words, you can use them like any other word. You do not have to mark them up in italics or enclose them in quotations marks or anything, just write:
"Ugh, that's disgusting," John said. Tsk, what a sissy.
The English interjection corresponding to the meaning you want to express with "tch" is tsk:
A sound expressing commiseration; an exclamation of disapproval or irritation. (OED; paywalled)
Best way is to treat it as verbal and use what are called interjections, words that have no grammatical meaning but convey emotions. So many different words convey these utterances:
The list can go on and on. Here's just one partial list of interjections.
A possible alternative is to convey it through the way the speech is delivered, such as "He snorted", and "he tutted", but this strikes me as a poor replacement.