my $mail = MIME::Lite->new(Subject => 'some_subject',
                           Type    => 'multipart/mixed');

# non MIME::Lite code here...

my $msgBody = "some foo message";
$mail->attach(Type => 'TEXT',
              Data => $msgBody);

#more non MIME::Lite code here...

for my $attachment (@attachments) {
   my ($filePath, $fileName) = split (/:/, $attachment);
   $mail->attach(Type        => 'application/octet-stream',
                 Path        => $filePath,
                 Filename    => $fileName,
                 Disposition => 'attachment');
}