What is it that your client wants to do with the pdf once it is uploaded? If you merely want to upload the pdf to the server, you could do it from the insert/update pages in any of the cart / short/ long description fields by clicking the 'link' button, selecting 'browse the server' and and from there selecting the browse and upload buttons. This should upload the pdf as a file and not an image.
The you can either choose to link to it or not, but the pdf will be uploaded to your server for whatever use you want to put it to.