Rears are easy. Just take off the battery cover or the CD changer cover off and the bulb sockets are right there. Twist counter clockwise until it clicks, about an 1/8 of a turn and the bulb and socket will pull straight out. Once that assembly is out, push the bulb down gently and rotate and it'll come out. Replace in reverse order.
Be careful with the type of bulb you use. I used a Sylvania bulb once and the "light out" light illuminated on my dash even though all my lights were working. After paying the dealer $150 to diagnose the problem, the tech found my non-Maserati bulb, replaced it and I've never had the issue again. So make sure you get the bulb from Maserati or find out what the exact brand and model the light bulb they use so you don't run into any problems.