Encode the subject line in MIME header using Perl 5.6

Hi,

I need to encode the subject line in a MIME header in UTF8 (something like 
Subject: =?ISO-8859-1?B?SWYgeW91IGNhbiByZWFkIHRoaXMgeW8=?=). I know that 
this can be done by using Encode in Perl 5.8. However, in my production 
environment, we can only use Perl 5.6 at this moment.

Is there anywhere to do the encoding in Perl 5.6? I would appreciate if you 
can provide an example to show how to do it.

Thanks and regards,
Wing