SMPTE/LTC timecode (which I'm assuming is what you're planning to use given the mention of 3-pin XLR) is basically just an audio signal. So, the hardware you need to get timecode out of the powerbook is an audio interface that has balanced outputs. Does your console actually have a 3-pin XLR inputs for timecode? If not, then it seems like it would make more sense to use OSC instead, and avoid the need for multiple interfaces.
My usual approach to syncing cues to music (with QLab and an Eos family console) is to do most of the work in the lighting console. The first cue in a given song includes an OSC or MIDI trigger to start playback in QLab, and a macro that starts the internal timecode. Since both are starting at nearly the same instant every time, they always run in sync with each other even though there isn't continuous timecode sent between them. A guy I work with does something similar with a bunch of follow/hang times in the cue list rather than internal timecode, but I find that method to be a lot more clunky--too much math at a time when I'd rather be looking at the lights.