/appengine-java-sdk-x.y.z/bin/appcfg.sh -A __application_id__ -M gaestudio update /path/to/unpacked/gae_studio
Running in development mode implies converting your application to a module. Then, you need to create an EAR application containing your app and GAE-Studio. The official App Engine documentation explains how to create the EAR application.
GAE-Studio is already declared as a module called 'gaestudio'.
You can run this EAR using the Java Appengine Tools (Google Appengine SDK for Java): /appengine-java-sdk-x.y.z/bin
/dev_appserver.sh /path/to/my/ear
.
The development server will start your app and GAE-Studio on two different ports. They will be displayed in the console output. ie: INFO: Module instance gaestudio is running at http://localhost:8081/