We have chosen a low-control / high-nurture approach, which seems to be working for us, but slowly. This means that we do not commission certain people as official mentors, or keep records of who is mentoring who, or make guarantees that we will match mentorees up with mentors.
What we do is to alert the whole church generally and prospective mentorees particularly about what to look for in a good mentor, train anyone who wants to be trained as a mentor, and keep telling the stories of how mentoring relationships are