The Grub configuration file is
Code:
/boot/grub/grub.conf
(in some distros the file name is menu.lst and some have both with one a link to the other).
If you mount the partition containing the grub.conf file for MEPIS, you can open the grub.conf files for Kubuntu and MEPIS in screen editors and copy and paste the MEPIS entry to the file for Kubuntu. You will probably want to increase the timeout value (in seconds) in the file too.