Cook the tortellini according to package directions, being careful not to overcook (it will fall apart when you try to skewer it; you may need to very slightly undercook it.) Drain and run cold water over the tortellini to stop the cooking and to chill the pasta.
Thread 1 piece of tortellini followed by a tomato, cheese ball, pepperoni slice, and an olive, and repeat (for small appetizers, use 6" sticks and only do the pattern once). Place the skewers on a serving platter or tray. If not serving immediately, cover and refrigerate until ready to serve.
Whisk together the pesto and Italian dressing. Immediately before serving, drizzle the skewers with the pesto/Italian dressing mixture.
If you have leftover bits and pieces that didn't make it onto the skewer (or you got tired of skewering), toss them together in a bowl, drizzle with the dressing mixture, and serve like a salad.