@spytfyre. The instructions for this years pilot are here
Basically we chatted to a number of neighbours we were already friendly with to gauge the appetite for it and discuss the logistics. If you are not sure about anything, for example, where to close the road, then email your local roads team (at the email provided) and they are happy to chat to you.
Between us we then proposed a date and edited the letter they provided on the site and put it through the other neighbours doors and tried to chat to as many other neighbours as possible.
We gave it a couple of weeks to give folk the opportunity to come back with any issues or concerns they had, then we put in the application to the council.
After a couple of weeks we got confirmation from the council that our application had been successful and then did another round of letters confirming the date and time.
The barriers should magically arrive in time for the start of the event (ours didn't but we just parked a couple of cars and used a couple of wheely bins) and the neighbours and children just started to appear.