Just found this post:
http://www.flynsarmy.com/2010/06/integrating-swift-mailer-into-kohana-3/
by Flynsarmy
showing the simplest way to integrate SwiftMailer and Kohana 3
Create the following files/folders:
/modules/swiftmailer
/modules/swiftmailer/init.php
/modules/swiftmailer/classes
Inside /modules/swiftmailer/classes/ drop the official latest build of Swift Mailer.
Enter the following into init.php.
<?php
require Kohana::find_file('classes', 'Swift-4.0.6/lib/swift_required');
There. Wasn’t that easy? Remember to enable the module by adding it to your bootstrap.php file!