The .LRN framework is very specific to the educational environment, with its classes etc. Packages are integrated into .LRN via some "glue" code - an "applet" which knows how to instantiate an application package for a user, or a class, etc. And a portlet which renders the actual boxes you see on the various pages.
It would be nice to have ETP integrated but it hasn't been done yet.
There is a very simple mechanism for adding text panels to class and club portlets - the "custom portlet" section on the class "control panel" page lets you create and/or edit them.