Is it possible to do this? What I'm trying to accomplish here is the creation of an extensible Struts 2 plugin with customizable screens to avoid code duplication in similar projects.
Yes, it is possible, but it has nothing to do with Struts 2: http://docs.oracle.com/javaee/1.4/tutorial/doc/JSPTags6.html#wp90207 (under "Packaged Tag Files").
Here is an example: http://www.examulator.com/moodle/mod/resource/view.php?id=473