You can just use the existing installer. It intalls correctly
However, it does not give full functionality. With that driver
installed, I can (for example) no longer print in monochrome.
I hope that HP releases an updated driver.
Actually, you can access the full functionality, albeit in an indirect way. If you bring up the print dialog from an old PPC app, or set one of the universal apps to open with Rosetta, you can access the printer specific settings. Simply select, as in your example, monochrome, and save that as a preset. Now, when you are in a universal app and want to print in monochrome, simple selct that preset.
PowerMac G5 Mac OS X (10.4.6)