What are the minimum requirements for a worker participation system?

The system has to be worked out in good faith between workers, their union, and employers. If agreement hasn't been reached after 6 months, a default option is included in the law.

Workers should not agree to any system that provides fewer rights than the legal default. However, there is nothing to prevent the parties from doing so provided it is done in good faith.

Until the six month period elapses, employers and workers must work together in good faith to elect reps, and negotiate an agreement.

As for the legal bit, the default system applies to the election of reps. You'll find it in Schedule 1A Part 3. In the current consolidated version of the Health and Safety in Employment Act, this is on p68-9.

Once elected, the rights conferred elsewhere in the act apply, for instance the right to training and paid leave - section 19E and 19F (p28-9).