#it's easy, mm-kay? a snippet from one of my scripts.
use Getopt::Long;

my %opt = ();
    GetOptions(\%opt,
        "rhost=s",    # remote host as a (s)tring
        "ruser=s",    # remote username as a (s)tring
        "rpwd=s",    # remote password as a (s)tring
        "localDir=s",    # local directory as a (s)tring
        ) or die "Invalid Command Line Options!\n";

#then use like this 

do_this() if $opt{rhost};
do_that() if $opt{ruser};
chdir $opt{localDir};

#etc etc
[download]