Well, then its apparent...
But, the "chaining" you are talking about doesn't pertain to MBR. Its pertains to grub once its running. Chain booting will point things properly.
As long as the MBR knows where the menu.lst is, it doesn't matter.
use which ever the "device.map" declares as hd0... in fact
grub-install hd0
from the running system should work without a problem.
Yeah, I know its scary. Try doing it remotely. :P