You can snag JSBuilder here.
Once you get it installed, you need to build a jsb3 file. Don’t try to build the jsb3 file on your own. The easiest way to create the jsb3 file is to use the following JSBuilder sencha command.
This command will generate a jsb3 file in the YourPath directory by munging the contents of your index.html.
This will spit out a lovely all-classes.js and app-all.js. You will then want to place the app-all.js in your production directory.