OK, here is my first thought of how to rig this.
PLEASE excuse my total lack of artistic ability.
View attachment 382641
The vertical brown line is a heavy beam, minimum 4x4.
The purple and green are a stop to keep the beam from sliding.
the blue line is a chain with a snatch block at the end.
The red is tour control line being able to go out the door to a car, ground anchor, couple of BIG people, or what ever else you might have as an anchor point.
You may even want to add another plate off the end of the stop to hook the doorway so that the bottom of the beam can not kick out while pulling from the top of it.
Do not use nails to assemble the beam, Ideal is bolts and nuts, second choice is lag bolts or other big screws MADE FOR WOOD.