Interaction between Berserk and crushing blow

[Herradura]

My primary character is a hardcore Freez-A-Lot and, obviously, the most dangerous part of the game for him is anywhere Iron Maiden is cast. One possible counter that I've seen mentioned is a Passion runeword with its +1 Berserk.

Is Berserk's conversion to magic damage done after everything else? Or is the crushing blow damage a separate amount of physical damage that would be affected by Iron Maiden? Or is it all handled some other way?

Thanks for any help, as it would probably be a good idea for me to find the answer before I start swinging my (future) Passion weapon while wearing my Gore Riders. ;)