Sadly it is very much a person by person process. In my experience with folks like this there are people they can "hear" advice from and those that they cannot. One option is to talk to their original PhD adviser (if they are still around) and get them on board. You and the adviser's interests are aligned, you both want the person to succeed and to do so they have to be able to hear your guidance on how to be better at the job. Sometimes they will be able to hear it from someone they have already put in the 'trusted advice' category.