Yesterday I had the unpleasant experience of having to go through my email to find an email I wrote back in February 2011 in which I detailed the steps required in order to perform an offline update of VMware ESXi hosts via PowerCLI. Had I posted the steps here on this site at the time, it would have saved me a lot of pain in trying to retrieve the email from an Enterprise Vault archive! So, as I have learned my lesson, I am posting the steps required to update ESXi from PowerCLI.