Or just use the st command line handler to load your code.
pharo-ui someimage.image st
blah.st
I do not know if it loads in Pharo5 but I had this working in Pharo3 that extends the File Browser in Pharo with additional buttons that allow you to edit external files easily.
Useful for writing scripts indeed.
Pharo can be used like Python, Perl, or Tcl for scripting from the command line.
VTermOutputDriver is an interesting class to look at for that (does nice colors).
Phil