To prepare the vinaigrette: whisk together the oil, vinegar and citrus juices in a small bowl and season with salt and pepper. Set aside.
To prepare the salad: in a heavy bottomed saucepan, heat 1 tablespoon olive oil over medium high heat. Add the couscous and stir about 1 minute, until the couscous is lightly browned. Stir in 2 cups of broth. Cover with a lid and reduce heat to low.
Simmer for about 15 minutes, or until the couscous has absorbed most of the liquid and is al dente. Drain in a colander but do not rinse. Place the couscous in a mixing bowl and stir in the remaining 3 tablespoons olive oil to coat and separate the grains.
In a serving dish, combine the couscous with crab meat, Kalamata olives, orange segments, pine nuts, scallions, cilantro, lemon zest and shallots. Drizzle in the vinaigrette and season to taste with salt.