You don't need to keep the app running. The app itself merely configures a launch agent, and that launch agent does the actual work of keeping your drive awake. Launch agents do persist across reboots. For more information, I recommend that you review the included Read Me file. :)
But to answer your question, you could copy the plain AppleScript file that is included in the distribution package to any convenient location you like, and then run it from the shell using the osascript command. Again, though, you don't actually need to do this.