From what little I've seen of the Mac version, it looks almost identical to the PC version.

Step 1: Get an audio file of whatever you want your character to say.
Step 2: Feed it into Mimic, along with text of the dialogue.
Step 3: Launch Poser and apply the newly-created .pp2 pose file to your character.

Automated lipsync doesn't get much simpler than this. The pose files will work with most of the human figures, and to a limited degree with others. Several figures (dog, cat, dragon, etc.) have been made Mimic-ready, and can be found in Free Stuff. Others can be adapted with minimal effort.

Video clip #1 (MPEG format, 335KB): Michael character
Video clip #2 (MPEG format, 231KB): Lionheart character (same voice as Michael)
Video clip #3 (MPEG format, 778KB)
Video clip #4 (MPEG format, 633KB)
Video clip #5 (MPEG format, 212KB): Lemurtek's Tobi character