Sorry for not getting back at this earlier. I thought I had it replied.
Coming to the issue, it does seem to be a known or common issue with VMware ESX and Blade server CDROM devices. The same is addressed here just in case, you haven't read it though.
As suggested earlier, you can try to copy the iso and continue your installation OR you need to make the cdrom devices as scsi targets and use them. But this way you wont be able to boot. This will defeat the purpose again.
Sorry to be of little help. I am still trying to find a blade server with multiple modules to try out your scenario and see if we could work around the issue.,