Edit Suses /boot/grub/menu.lst and add an entry similar to below
Code:
title Mandriva
root (hd1,X)
kernel (hd1,X)/boot/vmlinuz root=/dev/hdXX splash=silent vga=788
initrd (hd1,X)/boot/initrd.img
Make sure you replace the Xs with the right devices on which you installed Mandriva.