Initrd or Cdrom as root

[Hans K. Rosbach]

Is there any way to dynamically load initrd or cdrom permanently as
the root fs when booting from cdrom?

My problem is that I need a reliable way to ALWAYS find the correct
device to mount. Is there any way to make the kernel automagically
mount the cdrom it booted from?
I believe that for example SuSE installer cd does this, but I cannot figure
out how they do it.

If on initrd, I need about 300MB space on the root fs.

If this is not possible, what do I need to modify in the kernel?

-HKR