I have never done boot from SAN using iscsi. I believe you are using iscsi HBA's for SAN Booting. So manually register one of the HBA to unisphere, go to HBA Bios, scan the disk, save the path to boot from, install OS, create agentID.txt file and input same hostname you used for manual registration, install Unisphere Host agent which will register other remaining paths, go to SG properties, verify/add the additional paths (use engineering mode if needed), install multipathing software. thats it.

Thanks for the response.

Host Agent could pull/push array/host information automatically, I would suggest you install the Agent on the Windows hosts.