First SCP the installation file to the ESXi box and SSH over to issue the below command for install:
/tmp/OME_ESXi_plugin # esxcli software vib install -d /tmp/OME_ESXi_plugin/OM-SrvAdmin-Dell-Web-7.2.0-6945.VIB-ESX51i.zip
Message: The update completed successfully, but the system needs to be rebooted for the changes to be effective.
Reboot Required: true
VIBs Installed: Dell_bootbank_OpenManage_7.2-0000
Reboot to complete