I'm not exactly sure what you are asking. Most of the custom PS1 DVD covers on the site have been created using CD artwork that has been scanned at a high resolution. The back covers and spines of the DVD covers often use parts of the original CD scans but are pretty customized.
If you're asking if the CD artwork can just be printed and shoved into a DVD case as is, then no it doesn't really fit since the dimensions are quite different.