I tested and doing it in INIT works as you'd expect: import is called when the module is used, thereby replacing the function before the base one being replaced is defined. So the base ends up replacing the plug-in. But INIT is called right before execution so it does the job.

Regarding the evilness of this: Playing around like this is one of the ways I learned how Perl works. You will no doubt experience several lightbulbs going on as try different approaches, which is a good thing. Just think about your clients, the interfaces they use, and how much you may be bending standard views of the world before you turn what you play with into production code.