The door panel should not be pinched in by the windlace (the seal all around the door on the body). So, you should be able to take off the door panel with the door closed.
Remove all the handles, arm rest, and the two screws at the top at the front and back of the door panel.
The panel is held to the door by a bunch of spring clips on the sides and bottom. Get an "L" shaped prying tool of some type with a 1 1/2 to 2" long leg. Carefully work that leg under the door panel and pry that clip away from the door. Try to be near the clip and not between them or you could rip the clip(s) out of the panel - you'll know you're there because if will be a more snug fit than between the clips. I would suggest you start at a bottom corner, do the bottom first then work up the sides.
Once you've got all the clips removed, pull the panel bottom towards the seat and lift the panel up as it hooked over the door at the top. You may need to lower the window. You're done.
I have to add the discaimer that I have never had to pull the panel in this manner but have had a door panel off many times. What I've described seems to make sense.
I did look at the mechanism in the door at the latch area and the slim jim options looks like it might be a real challenge, at best.
Akron Don Gallimore
From: Donald Gallimore <dongallimore@xxxxxxx>
To: 1962to1965 <1962to1965mopars@xxxxxxxxxxxxxxxx>
Sent: Tue, December 18, 2012 3:52:18 PM
Subject: Re: Door won't open 65 Coronet
If you don't get any good answers, you could always pop the driver's door panel off and study the latch mechanism. Shouldn't take too much to figure how to get a home made slim jim in there to unlatch the door. I do have a '65 Satellite at home with the door panel off I could study and get back to you but it's not going to happen tonight due to a social obligation.
Akron Don Gallimore
From: cudaus1 <cudaus1@xxxxxxxxx>
To: 1962to1965mopars@xxxxxxxxxxxxxxxx
Sent: Tue, December 18, 2012 2:16:01 PM
Subject: Door won't open 65 Coronet
Hi guy's,
I need some help. My passengers door on my 65 Coronet will not open. I understand that most likely it is a U shaped clip that let loose on the lock rod. I purchased the clip, but how do I get the trim panel off with the door closed???
Any help will be appreciated!
Ted
65 Dodge Coronet 500
.