I've installed FFX squared 2.3, 2.4, and 2.6 on FF but neither came with executeable files. How do you create one?
You shouldn't need to. In your start menu there should be an FFX folder with a shortcut to launch the game. There's no specific FFX executable, only additional parameters passed to the executable through the game's shortcut file. Mind you, if you're using Steam, the shortcut might not point the the right file path.
If you need to recreate the shortcut, you can copy the default one, rename it to FFX and edit it (right click and select properties) to add the following at the end of the executable path:
-game ffx3 -log
More info in the game FAQ: http://freedomreborn.net/forums/index.php?topic=49868.msg680030#msg680030
Have fun with FFX!