SUSE has very appealing GRUB, so I would install Kubuntu GRUB on the kubuntu parition. then install SUSE, it should pick up kubuntu and list it in its GRUB. If not then, in SUSE /boot/grub/menu.lst add the following lines:
root hd(0,X) <----add the partition sector here e.g. if kubuntu is on /dev/hda3 this will be hd(0,2)
Note the case sensitivity.
You can find out more here http://forums.pcper.com/showthread.php?t=401513
saikee uses upper case, but this will only work in lower case