Hi i use four drives in my system, one ubuntu one leo (zeph v1) vista and a storage drive.
I unplug other drives except the one installing and allow grub , darwin or whatever to think its the only os.
Then do the same with the others.
At boot i can then hit f8 on my m2n4 mobo to choose the os.
This trick works in a lot of other board-bios combos to!.