Вопрос решен!
#!/bin/perl

use strict;
use warnings;

my $str = "some string";
my $hex = unpack('H*', "$str");

my $len = length($hex);
my $start = 0;

print "x'";
while ($start < $len) {
print substr($hex,$start,2);
$start += 2;
}
print "'\n";