We can't tell you exactly. At least not until you are the proud owner of this new hit of the seder.
What we can tell you is what your children and Passover guests will see:
They will see a beautiful Cup of Elijah sitting in the middle of the seder table filled with wine throughout the evening. When the time comes you will lift the cup and invite someone to open the door for Elijah to enter. You then say a few words, be they traditional or off the cuff, about Elijah truly coming this year. Encourage everyone to watch to see if Elijah drinks. Place the cup back on the table, let go, and the wine slowly disappears.
Cute, and perhaps a way to keep kids up until the end of the seder. But I have my objections to it. Adults shaking the table and joking that Eliyahu sipped is one thing. But having the come mysteriously drain as the child watches is another. This might, in some circumstances, constitute fooling our children in matters of faith.
Yet another good reason to read parsha blog every week.
Wherever I am, my blog turns towards Eretz Yisrael טובה הארץ מאד מאד