The RS::Handy module is just the single file, so you can copy Handy.pm to a directory called RS which is in Perl's path (@INC). On Unix systems /usr/local/lib/site_perl/RS/Handy.pm should work. See the output of "perl -V" to learn your perl's @INC.
Alternatively, you can download the properly-named module and simple Makefile.PL and use them in the usual fashion:
$ ls -l
total 65
-rw-rw-r-- 1 roderick roderick 61776 Feb 1 11:20 Handy.pm
-rw-rw-r-- 1 roderick roderick 102 Feb 1 11:17 Makefile.PL
$ perl Makefile.PL
Writing Makefile for RS::Handy
$ make
mkdir blib
mkdir blib/lib
mkdir blib/lib/RS
mkdir blib/arch
mkdir blib/arch/auto
mkdir blib/arch/auto/RS
mkdir blib/arch/auto/RS/Handy
mkdir blib/lib/auto
mkdir blib/lib/auto/RS
mkdir blib/lib/auto/RS/Handy
mkdir blib/man3
cp Handy.pm blib/lib/RS/Handy.pm
Manifying blib/man3/RS::Handy.3pm
$ make test
No tests defined for RS::Handy extension.
$ make install
Installing /usr/local/perl/RS/Handy.pm
Installing /usr/local/opt/perl-5.005_03/man/man3/RS::Handy.3pm
Writing /usr/local/perl/m88k-dgux/5.005/auto/RS/Handy/.packlist
Appending installation info to /usr/local/opt/perl-5.005_03/lib/5.00503/m88k-dgux/perllocal.pod
$ _
An advantage of using the Makefile.PL is that the man page will be
installed.
Roderick Schertler <roderick@argon.org>
http://www.argon.org/~roderick/