I am sorry, but I failed to understand what you mean.
Can you illustrate your goal, somehow?

ah like
the user is typing

hello
but the letters come out as sushi because the word sushi is in your text file?

Chrisir, yes!! that is exactly what i mean,

So, you just use keyPressed() as s trigger, ignoring the typed character, but displaying one char from the text.
It is simply a matter of displaying a text char by char using the keyboard as trigger, right?
Yes, it is possible, and quite simple. You don't really need a text box, actually.