While I've not pulled King from the locked door, any pet class can pull from a locked door with some extra effort.
Mages can stand up to a door, facing the door, cast eye of zomm (or the upgrade version) and the eye will spawn on the other side of the door.
There is a tinkered item with clicky eye of zomm - low trivial, for classes that can't cast it.
Though, King may still be too far away for this method (I'm not sure), so you may want to look into finding a clicky bind sight and keep binding sight up until you can target king.
I'm stopping short of saying any pet class can pull king, since king may be too far away for pet to attack when told to do so. One possible work-around for this, with the bind sight method, with each progressive target, send pet in to attack; before it engages, command it to guard that location - repeat. If you find yourself in a situation where you can command the pet to attack, but it does not respond to "back off" (too far away to command), summon the pet. There is a belt that drops in Veksar in church/priest area with unlimited clicky summon companion; though, I've only ever seen one drop from countless hours of farming.