yes, skip bootloader installation for other distros. just install it (or them) to second hdd. after installation edit grub.conf of fc3.
i have fc3 as main distro and others are slack 10 and centos 3.3
this is my second HDD:
Device Boot Start End Blocks Id System
/dev/hdb1 * 1 979 5863725 83 Linux --->/ of centos
/dev/hdb2 980 1709 5863725 83 Linux --->/ of slack
/dev/hdb3 1710 2491 6281415 83 Linux --->i will install another one ;)
all of distros have their own / partition. there is a swap partition which is /dev/hda7 is common for all distros. i dont have any /boot partition.
here is my grub.conf
title Fedora Core 3
kernel /boot/vmlinuz-2.6.10-1.737_FC3 ro root=/dev/hda1
title CENTOS 3.3 (2.4.21-27)
kernel /boot/vmlinuz-2.4.21-27.0.2.EL ro root=/dev/hdb1
title slack 10
kernel /boot/vmlinuz ro root=/dev/hdb2
i hope this helps u.