The goal of a coaching dojo is improving your skills by practice and by being exposed to various coaching styles. In Martins session at accde13 about Coaching Dojos we used the following setup:
|Coaching Dojo setup|
Split up into groups of 4-6 people. One person in the group will be your seeker. This should be someone who has a real-life problem/question he needs solved or answered. Nevertheless keep in mind that the goal of the coaching dojo is NOT to find a solution for the seeker but to train your coaching skills (although it might occur that the seeker's problem is solved). Next you need 2 people from the group that are the first to coach the seeker.
Do the coaching in timeboxes (we used 10 minutes). During this time the spectators watch and take notes (and most important: do not take part in the coaching!). When time is up, give feedback to the coaches. Usually most of the feedback will come from the spectators, as they are the ones watching from the outside. Then rotate the coaches and continue coaching, meaning the seeker will stay the same. Usually you do 4 rounds of coaching.
I thought it was exhausting talking a few times about my problem (in our group I was the seeker), so you can consider switching the seeker after a while (and with it the topic). I would leave this decision to the group.