[eluser]pistolPete[/eluser]
You can achieve this by extending the CI_Email class, I attached a sample class.
Put this file into ./system/application/libraries/.
I didn't test it, so please report back if it's working.
Using this extension you can attach a "virtual file":
Code:
// generate PDF
$file_contents = ... ;
$this->email->attach('filename.pdf', 'attachment', $file_contents );