Not possible, there is no such code in the game, so no way to enable it. Even AOE2 didn't have this originally, it was added later in The Conquerors Expansion.
UPatch HD - the unofficial (HD) patch for Age of Empires: The Rise of Rome - HD resolution, HD quality interface graphics, hundreds of bug fixes, new gameplay options and many other enhancements.
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Download here (version 1.1 Release 3).
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visit the site.