When I did it I did have an engine bay mounted engine holder bar thing so there was absolutely no chance of my engine rotating in the bay. I just mention this because you have to be careful when wiggling everything around while it's supported by a jack underneath. I have done the jack method before, and we used a piece of wood to support the engine by the headers I believe.
As for getting a seam, I wish I could remember exactly how I started a seam, I think I actually looked all around for any possible gap, if you get a very very tiny flat head, like one for small electrical components you should just be able to hammer it in the middle of the two parts and it should create a seam. Once you get it there you can just keep hammering in bigger flat heads.
https://imgur.com/a/pFc0HDn also in these pictures I circled in yellow where the pry points are, unfortunately I don't have a picture underneath it, but I believe the bottom of the tranny is flat, but it has like small rectangles in it and lines going from front to back and left to right, which the lined going left to right, you can put a pry bar between the subframe, steering rack, or sway bar and you should be able to pry it a little that way.
Also you should have most success if you can pop it closest to the bottom because of those studs that stick through the bottom of the tranny. but with that being said, if you can find a seam on the top, you can work it around with multiple flat heads until you get to the bottom of the tranny.
I think the reason they get so stuck is because the dowel pins become rusted and fill in the little gap that there is in the metal which makes it a super tight fit.
I hope this helps, and good luck! sorry for writing an absolute book of a response lol