DMT Schema Config Eclipse Plugin

First, download and install DMTSchemaConfigPlugin in your eclipse.

After the installation, when you select your packages which contains your Domain Object Model, you should be able see the DMT Schema popup menu.
DMT Config Plugin Popup menu

Click the menu, the Schema File Selection/create dialog will popup. If you want edit an existing schema, select the file, if want create a new one, enter your file name.
Select or create a schema file

After select or create a file, the following DMT Schema Config dialog will popup;
config dialog warning panel

The Name and version field is the DMTSchema name and verion you try to config.
If there is any class does not implement externalizable in your selected packages, the warning panel will appear to reminder you implement and copy paste the supplied code fragements to your class. (Note: future implementation will modify the class and generate the code for you)

Click the Default Options Tab:
Config Default Schema Spec
In the Default Excluding fields, you can edit the fields you want to exclude.

The externalizer config table, let you select your class and your externalizer to config
Config externalizer

In the DMT Schema Specs, you can config each class what attributes do you wnat to be included in this schema, for those don't have any attributes selected, the Default spec will apply.
Config Specs

After finish your editing, click OK, the schema definition file will generated for you according to your configuration.