Actually, you can dynamically change a textfield.type. AS2.0
You need two elements.
txt.type = "input";
txt.selectable = true;
However, if you have the textfield in a btn you will need to
delete the onRelease function before you can make the tf function correctly.
btn.onRelease = function()
{
delete this.onRelease;
this.txt.type = "input";
this.txt.selectable = true;
}