Actually two ways to do this. First and most expensive is an "electric hinge". (I'm not seeing them in the Von Duprin link). This is a regular usually 4"x4" mortise hinge that has been drilled and wires fished through it from leaf to leaf. No slip rings. (When you see one you are going to say "how the h*** did they do that?)
Cheaper way is to use a door cord to go between the jamb or buck to the door. This is just a short piece of flexible cord (like SOT) with blocks on each end that you screw to the door and jamb.
Either way, and the tricky thing is that you will have to cross drill the door for the wire from the strike location on one side to the door cord or hinge location on the other. If it is a fire rated door filled with plaster it may not be too much of a problem but with a solid wood door you better make sure your insurance is paid up. It's real easy for the bit to wander and go through the face of the door. Ouch!
Edit- For some reason I didn't see that page 24 thing first time- never used one but there is a third alternative.
-Hal
[This message has been edited by hbiss (edited 02-02-2005).]
