I did it! It took me all night, but I did it! I flipped the wheel the other way around and the rim got closer to the other side of the fork. So, dishing it should be. I created a tool from a long wooden piece with a bolt at each end tightened at exactly the same height and with a hole at the center for the butt of a vernier caliper to fit in.
It took a few tries and voila! Now it is dead centered. I did some sort of a mistake at first and all spokes where too tight. I loosened them all by half a turn and all looks good now.
After office hours I will take it out for a quick "look ma, no hands" test.