Adding attachments using PEAR

Hello,

I am writing a script that will email be backups of my websites.

I am going to add a zip file as an attachment to an email using PEAR.

To add zip attachments using PEAR I normally use:
$mime->addAttachment($file, 'application/zip');
where $file is the path to a file stored on the server.

Supposing I have the zip file stored in a variable e.g. $zip_file.

Does anyone know how to attach it without saving it to disk first?

Anyone know of a good online PEAR manual?

Megan help!