It really shouldn't be that hard. If you have problems with GRUB (such as it
not booting correctly/not installing correctly/incorrect boot options) simply
get a live CD (any distribution will do) and boot from that.
Then open a shell and mount the drive in question like so (usually /dev/sda):
# mkdir /mnt/whatever
# mount /dev/sda1 /mnt/whatever
# cd /mnt/whatever
# mount --rbind /dev dev/
# chroot /mnt/whatever
# grub-install /dev/sda
# update-grub
And that should provide you with a working GRUB. But be sure to grub-install
and grub-update once successfully booting into the system, as there could be
SELinux errors. Good luck.
