If your candidate regards himself to be a loner, explain how that could be a disadvantage both to the person and the organization.
Ask your candidate to write down what it costs him to help others, share knowledge, or ask others for help and what he gains from doing so.
Advice your candidate to go to places where people meet, look at their behavior and try and imitate such behavior.
Encourage your candidate to take notice not only of what another person says but also of what he signals with body language, facial expressions and attitude. How do the words and signals diverge in a conflict situation?
Encourage your candidate to ask ‘open questions’: questions that cannot be answered with ‘yes’ or ‘no’ (and often begin with ‘who’, ‘what’, ‘where’, ‘which’, or ‘how’).