I was able to create the next-best-thing , which is a bundled .app applescript file, saved from an applescript editor, which I put to live in the application scripts folder. The .app file is like .jsx or .vbs files because it will work when double-clicked, or performed file.execute() on. That file is set up to run a .scpt file of a constant name, which I write into the same folder, so by changing the contents of my .scpt file, this more awkward system is a bit more helpful on the Mac. The problems are that the warning yes/no dialog box pops up for files with "#target" in them, and that scripts sitting inside the Adobe Scripts folder do not even open. This is the applescript example:
do shell script "open -a \"ExtendScript Toolkit\" \"/Users/me/myFile.jsx\""
There's probably a much better way to do this, is there?