We need to call a custom class from a custom navigation button. We are looking for how to set the button configuration to call the class code, and also pass a reference to the current specification (context) that is being displayed as well as whether or not it's in edit mode.
I am not sure what's the exact purpose of you to add a custom class.
Generally, we support several ways to customize navigation. Please refer the "Oracle® Agile Product Lifecycle Management for Process Navigation Configuration Guide" included in Extensibility Pack Release 2.5 for detail.
(Extensibility Pack Release 2.5 is could be found on oracle support web site by patch number : 13485905)