RHEL5 32bit fresh installation without automatic PAE kernel

We need to automatically install RHEL 5 (32bit version, kernel 2.6.18-8) on a SUN X4250 with 8 GB RAM.

Does someone know why Kernel Pae is not automatically installed? After the reboot, it is possible to install the pae packages from CDs (and it works!) but we want an unattended installation with a PAE kernel.

In order to install a Pae Kernel (kernel-PAE-2.6.18-8) do I have to insert a special entry on my anaconda file? Is there a BIOS option to set? or anything else? With cat /proc/cpuinfo | grep pae it is possible to understand that the CPUs are pae compatible...

Please, don't suggest to update to 64 bit O.S because we have applications that run only on 32 bit.

Thanks in advance for your suggestions

Alessandro