UPDATE:

We learned that the laptop running MediaLab had a parallel port not 'strong' enough to drive the BioPac box. So we switched to a desktop computer and had good luck communicating between Empirisoft's IOTest utility and the Biopac system.

After further testing and removal of a small typo in the experiment file, we were rewarded with a properly running MediaLab experiment which triggered the Biopac system at the appropriate time.