Missing customized kickstart menu

Hello, I am attempting to install RHEL6.9 on an IBM HS23 blade. I have built up a custom kickstart disk that will display a menu of choices. The disk works exactly as expected on a VM and a more recent Dell laptop, but the (admittedly much older) blade skips the custom menu altogether. It does allow me to perform an interactive install, but that is not helpful.

In past versions you would be able to get to a boot screen and I could just type in my arguments (i.e. 'linux ks=cdrom:/ks.cfg') but now I can only get to GRUB.

Is it possible to install from GRUB in this way? Web searches have been useless because they all want to tell you how to install the grubloader.

Thanks in advance.