Excel 2010 :: Sensitivity Analyses - Dispersion Diagram / Chart

How to create a dispersion diagram which will show me the impact of 3 variables on oil-in-place, which for the sake of this description, I shall call 'X'.

The 3 variables (let's call them A, B and C as I needn't go into the details) are used in the calculation for X. I have created tornado diagrams, which show me the positive and negative impact of each variable. But I'd like to create a diagram with X along the x-axis, with X increasing, and on the y-axis, have -1 to +1 which represents the impact of the variables A, B and C on X. So, as X increases, variable A might also increase toward +1, which would show me that as variable A increases, so does X. The reason why I'd like to learn how to do this is, whilst a tornado diagram will show me the impact of each variable on X, a dispersion diagram will also show be trends between variables. So, for example, variables B and C might both increase along the same trend, which would show me two things: that they both positively impact X and that one variable is dependent on the other.

I remember from a few years ago that an old version of Excel had a data sensitivity tool which did something like this. I'm working off of Excel 2010 now, and I've had a little look at the 'whatif' functions, but that doesn't seem to be what I'm looking for. Also, I would kind of like to see how to do this myself with the raw data, instead of the behind-the-scenes stuff.