Thanks for the link, but that only addresses how to add different measures on a chart. What I wanted to do was swap measures in a calculated field and have a chart of that calculated field update automatically. I ended up finding the answer - you can do this using parameters and writing your formula in the calculated field to call out the parameter that is selected by a user. See:
I am also looking for this functionality. I have ~35 measures and I want the user to be able to select any combination of them, then use that combination in a calculation (let's say a weighted average). Have you found a resolution to your issue?