Booting external hard drive on multiple systems (GRUB Legacy)

[Vogel, Jens]

I like to create a linux installation on an external hard drive, which is 
bootable on any system, the drive is pluged in. I have no idea, how to create 
the mbr on this drive with grub legacy. In my opinion, the bootable partition 
(with /boot/grub/...) must be referenced relativ to the drive with the booting 
mbr or by uuid or something similar.

If i try to create the mbr by e.g.
# mount /dev/sdd1 /mnt
# grub-install --root-directory=/mnt /dev/sdd
it seems that there will be set an absolute reference to e.g. (hd4,0) in the 
mbr, which must fail on an other system with a different drive configuration...