We haven't been made aware of a way to do this yet from MSA, having said that if this were my helmet this is how I would install this;
first thing is make sure the crown sits correctly on your helmet(it has to fit under the back end of the holder) you might have to move it around to do this, next the hole in the back rib of the helmet needs to be lined up with the crown, you will have to drill a hole in the new crown so that it lines up with the hole in the rib, be sure to use a small drill bit and a variable speed drill motor. Once you have the holes lined up you can use a larger drill bit that match's up to the hole in the rib, after all of this i would get a pop rivet gun and pop rivet that fits the holes, and install it. Sounds like a lot of work to me MSA should have made this a lot easier, after all these years. Another thought could be super glue, were not recommending this but it's a thought.