winters, no problem at all, after all, you've got the degree in this department!
Anyway, ya there is another way to create stereo images as well where the left image stays on the left and the right stays on the right, and then you don't have to cross your eyes and you isntead just stare through the monitor as if you're looking at a distant object and if the images are the exact width of your eye separation, the stereo image pops out at you.
However, with different monitor resolutions and the limitation of smaller pictures, I don't like that method and it is just as hard if you ask me.
I find if you learn to use a small image set (like that posted last) is easier since you don't have to cross your eyes as much to get them aligned, then it makes your focus point more natural. From there, you can go to bigger images or further away and still focus.
Once you get it, its easy, I can focus on these images and even two monitors completely side by side with the cross eyed method in just a second or two if I stand back enough. I often slowly move forward once I am focused (really slowly) and your eyes will adjust automatically.
Good luck... !!