Use the esxcfg-auth command.

/usr/sbin/esxcfg-auth --enablead --addomain mydomain.com --addc mydc.mydomain.com --krb5realm=mydomain.com --krb5kdc mydc.mydomain.com --krb5adminserver mydc.mydomain.com

Replace your domain and server name where applicable. You will also need to add local user accounts on the ESX host by using the useradd command. You will need to open the firewall to allow kerberos authentication. Finally make sure that you have NTP setup on your ESX host to make sure that the time is in sync with your Kerberos server.