If you have another ESX host with all the users you need, you can copy the "/etc/vmware/hostd/authorization.xml" from that one to your new ESX host this grants the permissions. Then you can script the user account creation via the normal user add with "/usr/sbin/useradd -m -p <password> -c <username> -g users -G users -d /home/<username> -s /bin/bash <username>".
This is what I do in a postinstallation script so it's all taken care of for me at the begening.
Hope this helps!
