Does anyone know any more consistent way to make ISG happen than

1. set item half in portal
2. wave other item through it repeatedly like trying to cast a Harry Potter year 1 spell
3. keep checking for floor collision
4. grow old and die?

There are some glitch-hunting experiments I would like to perform but I figure after all of these years someone must have worked out a bit more about how to get this state started so I wanted to ask. :)