First, position the press using sockets or steel pipes of the right diameter. You need to push one end down and the yoke end below must be fully supported concentrically around the U-joint cap. The support is easy with a large socket. I have started with the splined yoke side first.
Press the joint until one cap is protruding. Grab the exposed cap in some vise grip pliers, holding the opposite end in a vise. Rotate the cap until free from the yoke. If you can't get the other side out, press it out opposite and repeat.
Now, repeat the above process using the axle or transaxle side yoke. Note that these yokes aren't flat on each side, requiring an angle-cut pipe or some ingenuity so that the pressing is completely straight. A wobbly part won't press out right and you'll quickly find that out if you try.
You should end up with this:
As a side-note, I found out that I need the end cap I was missing in the last post on half shafts to prevent grease from flying out of the open end. A 45mm hammer-in cap fits perfect, and I found one at a local machine shop.