I found this gem from John Nobile on social.technet.microsoft.com:
Instead of using IIS Manager to generate the request, you can do so manually. Opening the machine certificate MMC snap-in (mmc.exe -> File -> Add/Remove Snap-in ->Certificates -> Add -> Computer Account -> Next -> Local Computer -> Finish -> OK). Right click on the Certificates node under the “Personal” store. Select All Tasks -> Request New Certificate. When selecting the Web Server template from the enrollment wizard, open the template details and add both the machine name and fully qualified machine name of the web server as Common Names to the certificate subject.