I'm not a grub expert but I hate to see someone twisting in
the wind.

I know for sure that the SuperGrub utility can install Grub
(V.97, not the V2 that Ubunutu uses) onto a target partition
of your choosing.

But it also needs to be configured. Just guessing, but suspect
you could do that via a live CD boot.

I've only ever configured Grub a few times and it was fairly
intuitive, though you're probably going to want the man page
handy.

A possible foible is that for some reason you require grub V2.
IIRC you need V2 to handle more modern BIOS's.

I suspect this won't get you where you need to be, but maybe
it'll stir up some corrections or other input that you can use.