This was actually too simple, but unless you speak with support, how is one to know?
I was recently tasked with upgrading a server installation of Paychex Preview software, which according to documentation cannot be done on the host server, it has to be upgraded from one of the workstations via mapped drive. It seemed simple enough, until the point of the install "wizard" where it prompts for installation directory. It listed C:\RAPID, and had a dropdown menu so I could choose one of the mapped drives; but instead of listing mapped drives it only offered the local C:\ drive. No problem, the instructions on the screen said reboot if it doesn't list your mapped drive. Wait a few minutes for the reboot... and no good, just C:\RAPID again; time to call support.
After starting a WebEx session, so the tech could see what I was saying was true, we copied the RAPID directory from the mapped drive to C:\, then ran the Paychex Preview software upgrade on C:\RAPID. When the upgrade was complete, it was just a copy and replace over the RAPID directory on the mapped drive and the deed was done. Oh yeah, don't forget to run WS_Setup.exe from each workstation to create appropriate shortcuts to the mapped drive.