Here are some images of a simple adaptation I made to my dioptrx to fit my 45 degree prism. I simply super glued a stainless steel washer on the back. I think the hardest part is locating the washer - I happen to have a few extra - if you need one just send me an e-mail. I use the washer technique to make the whole thing easily reversible in just a few seconds in case you decide to wear your glasses or another photographer will use the camera.
Photo showing back side of retaining ring removed from the Dioptrx (click photo for larger view):
Photos showing installation after washer is affixed to retaining ring. You pull the rubber on the prism eyecup outward and slip the retaining ring over it. Then you fold up the rubber from the 45 degree prism into the retaining ring. Lastly you hold the Tele-Vue Dioptrx up to the eyepiece and tighten the retaining ring onto the Dioptrx. Don't tighten all the way tight - leave a little loose such that you can rotate the dioptrx into the correct orientation.
This is what the Dioptrx will look like from the photographers perspective. Overall it works quite well and since the Dioptrx is a bit larger, extends a bit from the prism and has its own eye cup, its actually a bit easier to view through. I suggest you focus the camera on something brightly lit and then rotate the dioptrx until the image gets sharp. You will also see the screen lines get sharp too. As you are getting close, you will see the vertical lines slope to one side or other - they will straighten when its just right and if you go past they will slope the other direction. So finding the correct setting is pretty easy. Tighten up the retaining ring when you have it correct.
Which power Dioptrx do you need? Have a look at your prescription for your eyeglasses and find the portion that shows the Cylinder and Axis corrections - that's your astigmatism amount. Find the one for the eye that you focus with - that's the power of dioptrx you need. Now if your prescription is mostly astigmatism and you've used a corrective diopter in the eyepiece you may find that you no longer need this. Or you can order a lower power. The best set-up is going to be a corrective diopter in the eye-piece that matches your sphere correction value, plus the dioptrx amount for the cylinder amount. Believe me, you'll be surprised by how well you can focus! I quit using AF after I got this set up for myself.