Simply uncompressing module tarballs or .zip files and putting them in a particular place isn't always going to do the job right. There's a standard procedure for installing Perl modules, and there's no problem with installing them into any directory to which you have write permissions.

perl Makefile.PL PREFIX=path/to/my/modules
make
make test #(optional)
make install
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The <coe>PREFIX</code> argument to Makefile.PL is the key here; if you omit it, the installation will point to the system-wide @INC directories, which are usually (because they ought to be) only writeable by the superuser. See your system's perldoc perlmodinstall for more goodies like this.

Philosophy can be made out of anything. Or less -- Jerry A. Fodor