Thanks for all the help to all. Here's where I'm still getting stuck. The following command in PowerCLI (version 4.0) works great to download a copy of the ESXi 4.1 config file to a local Windows workstation:
> set-vmhostfirmware -vmhost <hostname> -backupconfiguration -destinationpath <path>
Voila, the config file backs up and is in the specified local folder. The problem occurs when I want then take this config file (.tgz) and restore it to the ESXi host.
According to the PowerCLI help, the '-restore' switch has to be accompanied by a perameter that specifies a URL "retrieved via get-vmhostfirmware". The switch 'sourcepath' to point to a local folder isn't recognized.
There is indeed several web URLs the host has apparently created on port 443 such as https://<hostname>/tmp/, https://<hostname>/uploads/ , and https://<hostname>/downloads/ but I have no idea how I'm supposed to use these in conjunction with the set-vmhostfirmware command to restore a config file, nor how to get any files into these mysterious web URL. If you browse to them they just show up as a blank page.
Does this make sense to anyone? It would seem if I can backup the config file to a local folder, it should be just as easy to reverse the process, but it's not ending up working that way. Again thanks for all the advice and your assistance is greatly appreciated.