ActionScript 2.0 :: Inserting Text On Click?

I have a input text field on the stage and I want to insert text into that inputTF via a button. I can't use something like

Code:
add.onRelease = function(){
inputTF.htmlText = "hello world"
}

becase it replaces the user's inputed text. I want to just insert text where there "flashingType-dealy" is located (my apologies I don't know what it is called).

I think a starting point is using Selection

Code:
Selection.setFocus(inputTF);
Selection.setSelection(this.tempBegin, this.tempEnd);
//what else? //