I think exactly the same way, thats why I'm going to try the flush with Coconut oil then see if 'stones' come out. My guess is they won't. I must admit I do feel good after flushes but I believe its rather a combination of things which the flush involves rather than the 'flush' itself.
Update: Apparently you can't do the flush with coconut oil, surprise surprise.
2nd Update: Ok, what I'm going to do is do the flush as normal but buy a food dye so I'll make the olive oil bright purple or some distinguishable colour. If they are still Gallstones that are coming out then they should be unaffected by the die and remain green in the middle, I will forever hold my peace if they are.