Rescuing GRUB is very simple, you don't even
need the rescue disk for your system (it helps though), any bootable linux with support for the filesystem you use and your basic hardware is enough.
You need to know the partition where /boot is mounted (for example /dev/hda1) for your distro. Once you are booted into a working linux system (using any live cd), mount this partition on a directory, say /mnt/system, and then chroot to it (chroot /mnt/system), after that follow the rescue instructions for GRUB in the Linux Tips & Tricks thread
