How do I attach a drywall corner bead to a wood door jamb?
It seems to me that there are two possibilities here. If the opening in the wall is just a pass through without an actual door itself then you would band the opening with drywall material and then put normal metal corner edging around the outside corners of the drywall.

 

On the other hand if there is a door jamb in use with an actual door then the width of the jamb wants to be equal to the stud width and then the drywall is installed out over the edge of the door jamb and finished off with an end cap type metal edging.