use Modern::Perl;
use utf8;
use Encode;

my $text = "Gen 1:1 Ἐν ἀρχῇ ἐποίησεν ὁ θεὸς τὸν οὐρανὸν καὶ τὴν γῆν.";

$text = encode('cp1253', $text, sub{ sprintf "\\u%d\?", shift }); # cp1253 is for Greek)
$text =~ s/([\x00-\x1F\x7F-\xFF])/"\\'" .(unpack("H2",$1))/eg;

say $text;