[CentOS] grub/raid1 on centos4

With Centos3, fedora1/2 I have been able to put /boot on a RAID1
partition and have it boot normally.  Unlike earlier versions that
used lilo as the default boot loader, these did not make the 2nd drive
bootable but at least I was fairly confident that if the first drive
failed I could use the install CD in rescue mode to fix up the 2nd one
and go on.   However, Centos4 won't boot at all with a similar install
attempt and running grub-install in rescue mode gives an error about not
being able to find the bios drives.  Is there a howto somewhere to work
around this problem?

-- 
  Les Mikesell
   les at futuresource.com