You can't really highlight text in a form field, but if the field is set for Rich Text (on the Options tab in the Field Properties), then the text color and style can be controlled.
Rich text is a whole advanced scripting topic by itself. It uses the Span object. You can read about it here.
Thank you, but I can't seem to get close to what I want.
I am reviewing that link and it looks like it only shows how to make the entire field change text color and style. I just need certain words and phrases within the existing script to change color and style.
No, that link is to the "field.richValue" property. This is property that adds rich text to a field with an array of "Span" objects. Each span sets the text styles for a single span of text. Just like HTML. The examples show how it's done, and they do it using multiple spans.