For running jsx, read this: http://cookbooks.adobe.com/post_Communicating_between_JavaScript_and_t he_Creative-17383.html
ExtendScript has File.openDialog(), File.openDlg(), File.saveDialog() and File.saveDlg() Folder.selectDialog() and Folder.saveDlg()
the "Dlg" ones are instance methods which open from the selected location, and the "Dialog" ones use the default location.
Harbs