I'll preface this by saying I know just enough to be dangerous. But since you haven't got a reply yet, here goes...
in reply to Calculating the inverse normal distribution
Do you want the distribution function? Doesn't the mean and standard deviation determine that uniquely? Why do you need the target percentage?
I've seen the IGD page on Mathworld, and frankly I'd be concerned about coding that correctly, efficiently, etc. I note that Mathematica doesn't even have it yet.
Perhaps you can clarify your question (or perhaps it's just me in over my head).
Quantum Mechanics: The dreams stuff is made of