With the perldoc-search program, you can easily search all your perl documentation to find where that elusive "add_build_element" method is documented.
When I say this:
I get this:
perltoc - perl documentation table of contents
Module::Build::API - API Reference for Module Authors
Module::Build::Cookbook - Examples of Module::Build Usage
Now I know where to find documentation and examples of this method. Anyone who wants to extend this, it is available in github at http://github.com/jbenjore/App-Perldoc-Search/tree/master and CPAN at http://search.cpan.org/dist/App-Perldoc-Search.
I wrote this on the flight back from YAPC10. Just landed in Seattle.
Update: Aaaannnd, it appears Mike Schilli already wrote something similar. Somehow I missed it when I looked before. Dunno how, Perldoc::Search is such an easy name to find: http://search.cpan.org/dist/Perldoc-Search.