Step 1Pulse the olives, 2 cloves of garlic, the anchovies and rosemary leaves in a food processor. Add just enough red wine to allow the mixture to form a fairly smooth paste.
Step 2Score the fatty sides of the rib roast in a diamond pattern, using a sharp knife to cut through the fat but not into the meat. Smear the top and both sides of the roast with the olive mixture, season generously with pepper and let it stand at room temperature 30 to 45 minutes to marinate. Reserve any leftover olive mixture.
Step 3Heat the oven to 300 degrees. Carefully transfer the rib roast to a shallow roasting pan, bone-side down. Disturb the olive smear as little as possible. Roast to an internal temperature of about 115 degrees. This will take about 2 hours.
Step 4In a food processor, pulse the bread crumbs, remaining clove of garlic and the 1/2 teaspoon of rosemary until the garlic is minced fine. Remove the roast from the oven and pat the seasoned bread crumbs over top. Spoon over some of the fat from the bottom of the pan and return the roast to the oven. (If there is very little fat, sprinkle about 1 tablespoon of olive oil over the crumbs.) Continue roasting to an internal temperature of 125 degrees, about 20 minutes more.
Step 5Remove the roast from the oven, cover it loosely with foil and let it stand an additional 15 minutes before carving. Use the remaining tapenade to smear on the toasted baguette slices and serve it alongside the carved roast, dipped in the juices.