I am having quite the challenge using the vCenter Server & update manager.
First I found the great prepackaged Vcenter appliance (I expected it was logical to have one) and thought what an elegant solution. But then, while trying to figure out why I didn't have the Update Manager plug-ins, realized that the Update Manager isn't support with the appliance. Windows server only!
So suddenly the appliance is looking rather useless as that would mean having to run 2 vm's just to manage my single host. So it is looking like having to run a second Windows Server just to be able to update the host. During my initial tests I couldn't get the updates on the same host as the manager & server. It appears that you have to have these vm's on a SEPARATE host as the one you are updating. Now suddenly this is all very frustrating if I have to run VMWorkstation or have a second physical server.
So, I am wondering what other single host people are doing with their configurations.
Easiest way would be to download the patch bundles, store them on a datastore and run esxcli software vib install command if you do not want to have additional management overhead outside your environment.
Search for vmware patches in google. goto the first link you see and enter the build you want to upgrade to. Then download the patches and it willl create a zip file for you. Then upload it to some datastore and run the commands as mentioned in comment above
Check out Updating ESXi 5 - Single use esxcli How To for a step-by-step guide.