use File::BOM qw/open_bom/;
open_bom(my $fh, $filename, ':encoding(cp1252)');

##</code><code>##

use Encode::Guess;
open my $fh, '<:raw', $filename or die $!;
read $fh, my $buf, 1024; # may need bigger buffer for better guess?
close $fh;
my $enc = guess_encoding($buf, qw/cp1252 utf8 UTF-16/);
ref($enc) or die "Can't guess $filename: $enc";
print "$filename: guessed ",$enc->name,"\n"; #Debug
open $fh, '<:encoding('.$enc->name.')', $filename or die $!;