Creating custom ESXi iso image

Author : ygeorgieff

URL : http:////docs.vmware.com/en/VMware-vSphere/6.5/com.vmware.vsphere.upgrade.doc/GUID-C03EADEA-A192-4AB4-9B71-9256A9CB1F9C.html

Topic Name : Create an Installer ISO Image with a Custom Installation or Upgrade Script

Publication Name : vSphere Upgrade

Product/Version : VMware vSphere/6.5

Question :

Hi,  I am trying to create custom ESXi ISO image using mkisofs on a windows platform. I am executing below command .\mkisofs.exe -l -J -R -r -T -o 'customISO.iso' -b EFIBOOT.IMG -c boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -b EFIBOOT.IMG 'Vmware_ESXI_image'  The above command is generating the iso image but its not a bootable image.  What am I doing wrong in above command ?  Thanks, Ashish