The OP was correct, my intention from the start was to manipulate the loaded module before anything else could use it.

Anyway, I tried to do something similar, before I posted the initial question. Basically, in the @INC callback, it would remove itself from the @INC, use require to load the module in question, the put itself back in the @INC. The only problem was, that I had to somehow return a valid filehandle, otherwise, perl would continue down the @INC, and still load the module, even though I've loaded it beforehand, thus, overwriting my changes. The filehandle proved to be the most difficult task, since I had to return a filehandle to a valid file, yet, upon read, I'd have to just return '1;' as code, so as not to overwrite my changes. And I gave up at that point :)