Well I can say, that is a VERY good question. FOG is only intended to clone local block level devices. iSCSI is not necessarily in scope. With that said, it would be interesting to see it work. 😉
So let me ask you this, if you manually register this VM and then schedule a debug deploy task (tick the debug checkbox before you hit the the schedule task button. Then pxe boot the VM. This will drop you to a linux command prompt on the VM. So to the question (since you seem to be familiar with iSCSI) can you mount the iSCSI lun from the FOS Linux client? If you can then we might have a solution. I don’t know off the top of my head if the iscsi tools are install in FOG Linux (they should be but I don’t know for absolute). If you can connect to the iSCSI LUN then document the process so we can create a bash script to do the same.