[ericbsmith]

Last time I used Lulu it required you to upload images for the front and back cover, or to use the Cover Designer to help you create the cover (with or without images; you can do a cover with just text or even completely blank). At any rate, there was no way to upload a PDF to use as the cover. This suited me alright because I was printing compilations, so I was happy to create my own covers for them, and I'm reasonably competent image editing in Paint.net, Photoshop, and similar software.

One thing I will note is that if you use the cover designer then Lulu will put a UPC barcode on the back cover (you have some ability to control placement, but not much). However if you create a custom image to their specs they won't add the barcode.