Bootstrap conditionals are a different beast. Mathias wrote a post about them a while back that can be found here:
http://forums.wolflair.com/showthread.php?t=47611
For what you are trying to do, you would need:
That's it. I don't know off the top of my head when this tag gets applied to the hero, so I'm not positive what the timing would be.
That said, it would be far easier to bootstrap the tail attack to the Dragon Tail feat instead.