As long as the "2" is not used much in other ways in the doc, you can Find "2".
In the Change Format settings, click on Format and go to basic character settings/position. Select what you want. If you want scaling, you can check Indesign prefs/text/character settings for the sub/superscript defaults and replicate those or make others in the Advanced Character formats of the Change Format Settings.
Using OSX 10.3.9 on a G4