Meiwan is right, any Macbook Pro has a mini-Toslink/optical output inside the dual-purpose headphone jack. If you can't easily find a mini-Toslink to Toslink cable you can use a mini to Toslink adapter on a standard Toslink cable. The adapter is simply a spacer and doesn't have any effect on the optical signal. You might be able to find an adapter at Radio Shack but, if not, Monoprice is a good source.
