use Getopt::Long;
my $outfile = undef;
my $configfile = undef;
my $infile = undef;

if( ! Getopt::Long::GetOptions(
  "outfile=s", \$outfile,
  "infile=s", \$infile,
  "configfile=s", \$configfile,
  "help", sub { print "Usage : $0 --configfile C [--outfile O] [--infile I] [--help]\n"; exit 0; },
) ){   die "error, commandline" }
die "configfile is needed (via --configfile)" unless defined $configfile;

my $inFH = <STDIN>; # read input from stdin by default, unless an in file is provided
if( defined $infile ){ open $inFH, '<', $infile or die "opening input file $infile, $!"; }
my $instr;
{local $/ = undef; $instr = <$inFH> }
if( defined ($infile){ close $inFH }

# do similar for outfile and STDOUT
...

# and call your module translate, input text is in $instr
...