Interesting... You say that you hit the key and the lights die. In my experience that is a lose battery connection. Not saying that is your problem, but when you see what I'm talking about you see a quick little zap from the terminal, then I guess it kindof carbons up the tiny spot where it was making continuity, if you wiggle the terminals on the battery, then the lights come on. This is an interesting problem, not sure if anyone is familiar with what I am talking about.
Another thing, an alternator is not going to cause a no start condition by itself, unless its seized and you already know yours isnt. If your battery has enough juice, it doesn't need the alternator.
Something I would try, just a shot in the dark is un plug both connections at the alternator, the red power wire, and the electrical plug, maybe something shorted in the alt is kicking the power like I said above with the terminal arcing.