boo on you! you're supposed to have a good trick for me on that one!!!! so you've seen those too...those are painfully slow and tedious.
There is one trick I figured out in desperation changing a balljoint on the side of the road. Pull the dust boot off. And get a big pipe/monkey wrench.
You can grab the balljoint shell just around the collar that sticks out from the bottom of the knuckle. Twist the piss out of it, and MOST of the time that'll snap it free and it'll just come out.
This also works when you have a knuckle on the bench, you can do it in a vice.
If you have a spanner wrench or chisel, etc you can CAREFULLY and VERY SLIGHTLY open the crack in the knuckle. Like 1thou, or you'll break it. But that's often enough to get a bit of PB blaster in there. This is probably not recommended.
Another thing I've done is use a saw or thin cutting disc and cut the balljoint shell open between the slit in the knuckle (you know where the pinch bolt goes through). Now you can shove a screwdriver or punch or whatever and bend the casing a bit, this can help break up the rust and then you can twist it out.
The thing I usually try first is a bigass prybar between the control arm and bottom of the knuckle. A lot of the time this will break it free.
I did however break 2 ribs doing this when the prybar slipped out and I landed down on the front bumper of my GL....
Oh I almost forgot. I have a tool I made. It was a steel sleeve that was just bigger than the OD of the balljoint that sat down against the knuckle. It had a screw with a coupling that attached to the threads on the balljoint. And I had a hex head made to the top of the threaded rod. Hold it still while tightening a locknut and it would just suck the thing straight out. That worked fairly well most of the time. Sadly I have no pics of the tool, and it's in storage.