# emacs menu.lst
# dd if=menu.lst of=/dev/hda seek=63
4+0 records in
4+0 records out

# dd if=stage2 of=/dev/hda seek=67
385+1 records in
385+1 records out

# echo "install (hd0,0)/usr/share/grub/i386-pc/stage1 d (hd0) (hd0)67+386 p (hd0)63+4" | grub --batch

こんな感じで
ddを使ってセクタに書き込む