System | On start of layout (or whenever you need it)- Request whatever.json (tag "whatever")
AJAX On "whatever" completed - Array | Load from JSON string ajax.LastData
Really all there is to it...
Still having trouble, upload a .capx and someone'll help, i'm sure!
EDIT: oh, one more thing, and I'm not positive it matters, but it might, aside from the very beginning and very end, my JSON files don't use any of these brackets: { }, only these: [ ]
I think it might have to do with the setup of your JSON file...
see if this makes sense, starting at the word "data"
"data": [[["x0"], ["x1"], ["x2"]],[["y0"],["y1"]],[["z0"],["z1"]]]}
at least, looking at some of mine, that's the format they're in.
hope that helps!