Olive oil does the main job. Epsom Salts help to smooth the whole process and help to get rid of the released stones as soon as possible.
Grapefruit juice is the best thing to add to your flushing drink, so you can drink oil without too much problems.
Once I flushed with olive oil and fresh beetroot juice, just to prove to some "potential Liver Flush fans" that those green stones are not product of oil and juice (they would get some colour from beetroot). The flush went as usual and stones were green as always.
I prefer to do it with grapefruit juice. It just tastes better.