 <p>I ended up discussing the situation with InstallShield (made by FlexEra) and they recommended the following:</p> <ol> <li>Don't put the original file in the [InstallDir] if possible.</li> <li>Create separate Components for each of the variants of the file, each with a different release flag.</li> <li>Only install the Components associated with the release flag you want.</li> </ol> <p>This partially addresses my question but not entirely, because it doesn't let me specify a new file at install-time; I can merely select among existing files.</p>