Nonetheless a good question Conrad. Personally I have used it in training more from the view of how to 'get out' of one rather than how to do one.
If shimewaza is applied properly, the more you struggle or "try to get out of it" the more effective it is. If you can get out of it, it hasn't reached kime yet. Skillful application causes the arms/hands to go away from the core of the body and panic sets in almost instantly. As Fred Little says, voiding and soiling one's trousers is likely as the affect deepens. It doesn't take very long when done properly. It isn't really about "choking"...
It's too bad we lost much of this discussion when the server went down.