Adding new Gentoo installation to already-installed GRUB
So, I've been working on getting 3 OS's on my computer: Vista, Ubuntu and Gentoo. Vista was already installed, and Ubuntu did most of the work for me. I just got done installing Gentoo now. However, Ubuntu installed GRUB already, so now it appears that I need to go back and manually add Gentoo to the bootloader. I've looked at the Gentoo documentation for configuring the bootloader, but I've run into an obstacle: I'm not sure of what kernel image I have or of my initid image, if indeed I even need it. I installed Gentoo using the 2008.0 LiveCD (i686). I'm also confused about the "root hd(0,0)" stuff (I'm a bit of a noob), if someone wouldn't mind clearing that up as well.
I can access the volume that I have Gentoo on using Ubuntu if that helps.
Thanks in advance!