no gentoo isn't compltely installed, i'm at the end of the install and the directions say to conf lilo. i typed in:

boot=/dev/hdd
map=/boot/map
install=/boot/boot.b
prompt
timeout=50
lba32
default=linux
image=/boot/kernel-2.4.20-gentoo-r5
root=dev/hdd3
initrd=/boot/initrd-2.4.20-gentoo-r5
append="root=/dev/hdd3 init=/linuxrc"

image=/mnt/mandrake/boot/vmlinuz
label="Mandrake9"
root=/dev/hda1
initrd=/mnt/mandrake/boot/initrd.img
read-only

and /sbin/lilo and got

Warning: BIOS drive 0x82 may not be accessible
Warning: /dev/hdd is not on the first disk
Warning: BIOS drive 0x82 may not be accessible
Warning: Unable to determine video adapter in use in the present system
Warning: BIOS drive 0x82 may not be accessible
Warning: BIOS drive 0x82 may not be accessible
Fatal: Image name, label, or alias is too long: 'kernel-2.4.20-gentoo-r5'

could i just reboot and config lilo from mandrake?? i am unsure if it is installed for mandrake but i coud urpmi and go from there?

You need to have both distros installed fully first - then even if you can only still boot into one distro, its a simple matter of mounting the other distro's partiton that contains its kernel then adding an appropriate entry to lilo.conf then running the map installer /sbin/lilo - so first of all make sure youve installed both distros first fully.