If it comes to using man, it doesn't matter where you put your POD. In fact, you don't even have to install it. See, man reads man pages, which are in *roff format. man cannot parse POD.

It's when you install your module when POD gets turned into manual pages, and gets installed.

Now, perldoc, that's a different matter. That does on the fly search and parse. perldoc search @INC. Which basically means that if perl -MModule -e1 compiles, perldoc can find the POD for Module.