Article 52 sounds like a very good book. I'll have to add it to my wish list. From what I know and have seen of Paul Gordon, he is a very clever magician and creative magical thinker.
This may not be for everyone, but the following is my own handling and script for how to do an Equivoque with 5 piles of cards (or five anything, really). Start out by saying, "OK, we are going to eliminate some piles. Please choose 3 of the piles." Once they do this, there are now two possibilities:
Possibility (1) either none of the 3 piles they choose is the one you want to force; or Possibility (2) one of the 3 piles they choose is the pile you want to force. Below is the handling for each of these possibilities:
Possibility (1) None of the 3 piles they select is the "force" pile. Start by saying, "All right, we will eliminate the 3 piles you have indicated. [And you take those 3 piles away]. Then say, "This leaves us with 2 piles. I would like you to choose one of them." If they point to the force pile, I would say, "All right then, we'll use the one you've chosen." [Get rid of the other pile, and you are good to go]. If however, they point to the non-force pile, then say, "OK great, then we'll eliminate that pile, as well." [Again, you are good to go].
Possibility (2) One of the 3 piles they choose is the "force" pile. In that case, say, "OK, we'll eliminate the other 2 piles." [And you take away those two piles]. Then say, "All right, 3 piles now remain, would you please choose 2 of those piles." [If they choose the 2 non-force piles, you say, "Great, we'll eliminate these piles as well." Follow up by saying, "So you have eliminated all but one pile." [And you are done]. But, when you get to the stage above where you say, "All right, 3 piles now remain, would you please choose 2 of those piles," let us suppose they choose two piles, one of which is the force pile, and the other a non-force pile. In such a case, then keep those two piles they have chosen and get rid of the other (non-force) pile, saying, "OK you have chosen these two piles, we'll eliminate this one." Finally, say, "All right, 2 piles remain, would you please choose one of them?" If they choose the force pile, then take the other pile away, and say, "All right, you have chosen this pile. [And your mission is accomplished]. But, if they choose the non-force pile, then say, "OK, great, we'll eliminate that pile as well." [i.e. the non-force pile] [Again, mission accomplished]. You can now say, “You have eliminated all the piles but this one."