Here is a very good article: http://www.linuxjournal.com/article.php?sid=4622
I guess you also have copied the relevant files (kernel, map etc) to /boot. What you need to do now is:
which will create a /boot/grub/menu.lst file. Read the above mentioned article to edit hard drives in case your /boot directory is on another partition than / directory.
(hd0,0) first partition of primary master hd
(hd0,1) second partition of primanry master hd
(hd1,0) first partition of of primary slave hd
2) Create a bootable flloppy by:
"mkdir -p /floppy/boot/grub"
"cp /usr/local/share/grub/i386-pc/stage* /floppy/boot/grub"
2.2) Write grub to mbr of the floppy
2.3) copy the edited menu.lst to /floppy/boot/grub/menu.lst
3) rstart from floppy
If your system starts up correctly, copy the menu.lst in /boot/grub/menu.lst and install grub in mbr of hd with "grub-intall".
good luck and have a look at the article given above.