You need to set an absolute value for the leading rather than using Auto.
And maybe creating and applying Character Styles to these word(s) would have a number of advantages over the way you're working at present (This tutotial is for InDesignCC but I would have thought it would be similar for CS4):
When using Automatic Leading, the line height adjusts to accommodate to the largest size on each line. But you can change the *scale* of your text, as this will not change its *point size* (as far as InDesign is concerned).
Set the Width and Height to a number larger than 100% to do so. Make sure you use the same numbers, else you'll get weirdly stretched or compressed text (well, unless that's the effect you are after).
Apply this with a Character Style, so you can easily tweak it when necessary.
Have incorporated the above suggestions of using Character styles along with absolute values … SNLippert -- thanks!