Download and install the software from Prodesigntools.com and then use your serial number to serialize it.
This is not helpful as CS4 Production Premium can not be downloaded here (URL not found). I too have CS4 Production Premium but lost disc 4. Any other options?
Please read the download instructions carefully before downloading the application.
Hope It Helps
You can find the CS4 portion of the Prodesigntools.com site at http://prodesigntools.com/download-adobe-cs4-and-cs3-free-trials-here.html. As _Techkid123_ stated please make sure to review the page in detail prior to clicking on the link to initiate the download.