The Application Builder makes it easy to find the script. Choose
Build > Edit Script
or click the 
toolbar button. Edit the script using the Editor tool that this displays. See The Editor for more information about using the Editor tool.
Before it starts a build, the Application Builder saves the editor buffer displaying the script if you have modified that buffer. This behavior can be switched off - for the details, see Configuring the Application Builder.
LispWorks IDE User Guide (Macintosh version) - 12 Feb 2015