well, there are no stupid questions, just stupid people. nah, just kidding you did it the same way i would have, in fact i just did almost the same thing. all you have to tell grub is the root drive and the relitive location of the kernel you wish to boot.
grub starts counting drives at 0, then 1, then 2 and so on. im assuming that your 2 hd's are on the ide chain. so here goes what i think the added menu entry in the grub.conf file would be,
title Madrake linux
root (hd1,0)
kernel /boot/wherever/the/kerenl/would/happen/to/be
boot
you have to know where the kernel is to boot it, i hope that this helped