Once in a while you will need to install a system thats not on the network and instead of manually installing it you want it automated with a kickstart file. For most hosts you can create a floppy image with the kickstart file and mount it however on most Dell servers due to the way it handles the device names it can be tricky and this is where a custom cdrom can help.
- download the dvd iso
- mount the iso.. mkdir dvd; mount -o loop rhel-server-7.2-dvd.iso ./dvd
- create a temp directory and copy over the files.. mkdir custom; rsync -ravt ./dvd/ ./custom/
- make the customization like copying the ks file and editing isolinux.cfg to add the ks=....
- create the custom iso
mkisofs -U -r -v -T -J -joliet-long -V "RHEL-7.2 Server.x86_64" \
-volset "RHEL-7.2 Server.x86_64" -A "RHEL-7.2 Server.x86_64" -b isolinux/isolinux.bin \
-c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table \
-eltorito-alt-boot -e images/efiboot.img -no-emul-boot -o ../rhel-server-7.2-custom.iso .
couple of items to note. volet and -A need to match whats in the isolinux.cfg.
There were other ways to create the iso however I found that if the above command was not used on newer hardware it had trouble booting.