Installing grub in a partition not in the MBR

[pardon?]

hi,
My hard disk is organised as:

/dev/sda1 1 16379 131556348 7 HPFS/NTFS
/dev/sda2 * 16380 18246 14996677+ 83 Linux
/dev/sda3 18247 30401 97635037+ 5 Etendue
/dev/sda5 18247 18495 2000061 82 Linux swap / Solaris
/dev/sda6 18496 30401 95634913+ 83 Linux
sda1 is my Vista partition, sda3 is my Ubuntu 9.10 / partition and sda6 my /home partition.
Note that I've moved the boot flag from sda1 to sda2. I've installed 9.10 using the installer from the LiveCD and all works well but I wonder: if I have to re-install Grub2 for a reason how can I do it?
My question is: how can I, using the cli, install Grub2 in the sda2 partition instead of the MBR. Which command can I use.
Using:

$ sudo grub-install --root-directory=/... /dev/sda
will install grub2 in the MBR if I'm not mistaken. And when I do:

$ sudo grub-install --root-directory=/... /dev/sda2
It reports an error.

[louieb]

GRUB2 gripes about being install in the boot sector of a partition. I had to use the --force option. Complained but did it anyway.
IDBS GRUB2 Linux bash Commands (http://members.iinet.net/%7Eherman546/p20/GRUB2%20Bash%20Commands.html)

[pardon?]

Thanks louieb.
If I understand you you use grub-setup instead of grub-install. It's not exactly clear for me which command to use. Thanks for the link too. I'll read it carefully.

[oldfred]

Ubuntu does not use the boot flag. That is a windows (and maybe some other systems) thing. You can move it back to the windows partition without problem.

I installed grub2 to the partition when I installed alpha. At that time it did not complain, but now on every update I get the warning message about blocklists. System works fine, I currently chainboot from an old grub only partition to grub2 in the Karmic partition.

[pardon?]

Ubuntu does not use the boot flag. That is a windows (and maybe some other systems) thing.

Yes but if i don't move the boot flag to the Ubuntu partition then when I reboot, the BIOS starts Vista instead of Ubuntu. That's why I've done it.

[louieb]

Your right - think i did use grub-setup. That was just after the beta came out. - All I known I'm chainloading Karmic from GRUB legacy in my Jaunty install.

About the boot flag - thats kinda weird - did not know that some BIOS look for the boot flag. :DI'll have to put that in my odds and end bag.