Then you can just extract encoding function from this module. Here's the example that encodes header into Base64:

use strict;
use warnings;
use utf8;
use Encode;
use MIME::Base64;

sub encode_header {
    '=?ISO-8859-1?=' . encode_base64( encode('iso-8859-1', shift), '' 
+) . '?=';
}
print encode_header("!Hey‘ This is a αινσϊδλοφόρΡ mail!");
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Note, that Encode is a standard module, and you need MIME::Base64 to use Mail::Message::Field::Full anyway.

Yes, thank, but finally I used a tiny module that comes with MIME::Lite

 use MIME::Words qw(encode_mimewords);
 print encode_mimewords("Me and \xABFran\xE7ois\xBB in town");
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thank guys