It’s been a week now and I still have had no success installing all 3 major OSes on my MBP. OSX+Windows works fine (via Bootcamp), OSX+Ubuntu 9.10 also (9.04 hangs on boot).

This, however looks promising:
http://tubeshards.wordpress.com/2006/12/05/install-windows-to-a-macintosh-usb-drive/