I think this would work for him if you could load up the mime attachment programatically. I just tried but it doesn't seem to work. I did the following:
var file = new File("/some/file/here.txt");
var mimeAttachment = new MimeAttachment(file);
System.log(mimeAttachment.content);
System.log(mimeAttachment.mimeType);
It seems like this should work but it doesn't. There is no content. The mimeType does show as text/plain but I can't get any content to be displayed. If I use the same file as an input and manually select it then it works. Bug or design?
Paul