yes, there is...
in your menu.lst file, do somthing like:
title Gentoo Linux
root(hd0,0)
kernel /boot/bzImage root=/dev/hda3
vga=ask
I just set this up the other night...
of course you can do this from the GRUB shell, too.
just about any parameter you want to pass too the kernel can be on the kernel line in GRUB
but I'm pretty sure this will only work for Linux...you can check out GRUB more fully here:
http://www.gnu.org/manual/grub-0.90/grub.html