GWW- Frank is describing perfectly. We did a couple small tweaks. I made an image of the profile at the desired rotation in a textbox that was 1.5x 3.5 (about 3 fit on a sheet of paper) We cut one out and tape it (lots of tape) to the end of one of the boards (2 by 4s in our case). We leave the end sides of the profile uncut to support the board while we make our other cuts. So we started cutting about 1/4" in from one side, ripping the whole board up to the root (as Frank said, we used a stop to keep the board from going all the way and this left the root full thickness-in our case, it was a sawhorse with a piece of plywood screwed to it so the board ran into it at the end of the cut, then we'd lift it up).
To set the height for each cut, Dan would push the board on the running blade until the top of the blade was at the taped-on profile at the end of the board. He would then slowly raise the blade until I told him to stop (when it touched the line of the profile). Then we would rip each board all the way to the stop. Since the fence stop, the length stop and the blade height were already set, running the other two blade blanks through was just a matter of pushing them through).
Then we move the fence over about a blade width and repeat.
Once the cuts are all made, we spray the grooves with black paint and then just sand them down until the paint is gone.
If your blade profile requires a taper or twist, this probably won't work for you, but for a straight blade it's easy.