I promised an update. Unfortunately, here it is:
I updated to the most recent PPD and firmware for my 44" Z3100ps GP. With the current versions of each installed, I can no longer access any custom papers. The printer utility only has limited functionality. Printer status shows an icon of a laser printer and yellow exclamation marks for each ink color until I click on the printer details button, at which point the normal icon appears and my ink levels show up. More of an issue, though, is that when I click on Manage Papers, it says that it cannot get the custom paper list, check to see if the printer is connected.
I called tech support about my problem, and they had me throw away addl. PPD files in my Library, uninstall and reinstall the Printer Utility, and repair permissions. None of this has helped, and they are currently out of ideas aside from a clean system install. HP still does not seem to have it together with releasing installers that work without major manual tinkering. For me, this update is a failure. To top it off, APS was working for me with the previous PPD and the raster driver, and it now is unable to communicate with the printer.
-Ron H.