In Fireworks CS3, if I wanted to spread text out, I would create text of, say, 48 pixels, centre-justified - eg 'driving school'. I would then use the 'justified-aligned' (the right most text justify button) to make the individual letters spread out across the text box. If the font size was 48 px, it wouldn't change but take the font size down to 24 px and the physical size of the font would halve, the text box size would remain the same size and the letters would spread out evenly across the text box - eg 'd r i v i n g s c h o o l'.
In CS4, when I 'justify-aligned' and reduce the size of the font, the text box merely shrinks and the text fills it. Even when I drag the size of the text box to the right, the space between the letters stays the same and the two words get justified left and right - eg 'driving school'.