How to add a Domain user to have Admin permissions into Vsphere 4, NOTE: don't have Vcenter

Hi

Is there a way to have a Domain User or Group  (defined previously into Domain controller )  defined with Admin permissions into

Vsphere 4 ?   i don't have Vcenter   only  Vspohere 4  for  ESXI 4 Upd1    don't have  ESX   JUST  ESXI

Thanks