Importing download urls to MarketPress

I want to import a large number of products into my marketpress store. About 3500.

About half have a download product.

Do I have to use the media manager to first import the products and then get the link from there? I would rather create a directory and just ftp all the products to that directory. I have no need to access the products stored that way except as the download.

Also, will relative links work on the download url, or do they have to be absolute?

Thanks
Chris