There is no way you can install GRUB or any other bootloader in a partition. You need to read more about MBR and Bootloaders. The GRUB installs in the MBR which are the first 512 bytes of HDD, period.
Now if you try to do it, you will, and I say will not might, cause several issues to your installation.
If you want to keep your "pretty nice boot menu", go to the vendo'rs page and see how to add manually the entry to that menu for the BT.