I'm afraid this is a bit of a draw back of the pivot table, when you format the table in this way the cyclical button disappears - an annoying bug that's caught me out. Conditional Display is not available for the pivot table - at least not on version 10 which I'm currently on.
My solution was to create a listbox for a data island (as Adam suggested) and use this to drive a single expression. Within this single expression, each of your previous expressions are calculated (but only if they are selected in the list box - I used a variable for this) and added together.
I also put some text in the header that was dependent upon this selection, so the use always knew exactly what calculation they we looking at.