You must create a custom message catalog to override any string that is defined in the default message catalog. For example, if you want to rename Identity Manager, you must create a custom catalog and change the following definition:
PRODUCT_NAME=Identity Manager
The following entries also control the display of the product name:
LIGHTHOUSE_DISPLAY_NAME=[PRODUCT_NAME] LIGHTHOUSE_TYPE_DISPLAY_NAME=[PRODUCT_NAME] LIGHTHOUSE_DEFAULT_POLICY=Default [PRODUCT_NAME] Account Policy
See Chapter 8, Customizing Message Catalogs for detailed information about creating a message catalog.