The GUI for configuring GRUB 2 in KDE System Settings is a KDE control module named kcm-grub2. It works with the GRUB 2 schema used in other distributions, but not with the GRUB 2 schema used in SL. Below I list the differences between GRUB 2 in Gentoo and in SL, which is why kcm-grub2 does not work in SL.
Gentoo GRUB 2:
Main directory used: /boot/grub2/
Directory in which GRUB 2 core.img file is stored: /boot/grub2/i386-pc/core.img
Command to install GRUB 2 in the MBR of HDD sda: grub2-install /dev/sda
Command to create grub.cfg file: grub2-mkconfig -o /boot/grub2/grub.cfg
Sabayon GRUB 2 before GRUB 2 Version 2.00:
Main directory used: /boot/grub/
Directory in which GRUB 2 core.img file is stored: /boot/grub/core.img
Command to install GRUB 2 in the MBR of HDD sda: grub2-install /dev/sda
Command to create grub.cfg file: grub-mkconfig -o /boot/grub/grub.cfg
Sabayon GRUB 2 now:
Main directory used: /boot/grub/
Directory in which GRUB 2 core.img file is stored: /boot/grub/i386-pc/core.img
Command to install GRUB 2 in the MBR of HDD sda: grub2-install /dev/sda
Command to create grub.cfg file: either 'grub-mkconfig -o /boot/grub/grub.cfg' or 'grub2-mkconfig -o /boot/grub/grub.cfg' (grub-mkconfig is a symlink to grub2-mkconfig)

