Piece of cake.
I assume you have SuSE installed already. Next step is to create a partition to install Kubuntu. Remember that doing partition manipulations has to be done on unmounted partitions. So, if you can boot Kubuntu as a live cd, do that so that you can create your new partition. If the partition is already made and formated, you're ahead of the game.
Install Kubuntu. When you get to the part about where to install grub, be careful to specify 'root partition', not MBR. Though it doesn't matter a whole lot, because what you have to do to make dual boot is the same either way.
Once Kubuntu is installed (which should write /boot/grub/menu.lst config file), the next thing to do is mount the SuSE partition so that you can get to SuSEs /boot/grub/menu.lst.
Copy menu entry from Kubuntu /boot/grub/menu.lst, and paste it into SuSE /boot/grub/menu.lst. Or do it in the reverse order if you decide you want Kubuntus grub controlling the boot menu.
Reboot, and you should see both SuSE and Kubuntu in the grub menu.