I removed the retaining ring using a 5/8" (IIRC) bolt head and then the retaining bolt (?) with an 8 mm Allen wrench. Now I'm stuck!
How do I remove the crank arm? I pried slightly with a piece of pine and I hit the arm slightly with a rubber hammer. I don't want to be savage - I don't have experience with CF and I don't know how much abuse CF products can take, so I'm being somewhat gentle. I couldn't feel a large lip that would allow me to tap it through the center of the crank from the other side. I am able to rotate the bearing race housing (?) behind the crank arm.
There's no damage, I just want to re-install the original compact crankset.
This is the overview with the retaining ring and the actual retaining bolt sitting on the rear tire.
Unfortunately the close-up didn't come out well but it still might help.