If a Job script is not stored on your Repository, if you created it manually in a text editor for example, you can always open and edit it in Talend Studio.
To do so,
In Talend Studio, click menu File, and Open/Edit Job Script. An [Open/Edit Job Script] wizard displays.
Browse to the jobscript file you want to open and select it.
Click Open. The jobscript file opens in the workspace of the Integration perspective of Talend Studio. You can modify the script if needed and save your changes.
Jobscript files can be opened and edited in the Studio but they cannot be saved in the Repository.