I don't know a lot about man trailing, but I am trying to tell you how to make your dog track, so follow a path in a meadow, that can be either your own or one from another person.
I learned this method when I did this great seminar in April this year with Bernd Föry & Melanie Krüger, who took part in several FCI-championships. They also use a very positive training method.
This is Elliot at the seminar on his 5th track:

First, you should not take very smelly food, because you want to teach the dog to stay on the track and not look for food. Food should only reward him for using his nose. Really hard, dry food is the best. And take really small pieces of it. First you would stamp on a square maybe 40 on 40 centimeters. While your stamping on it, you drop various small pieces of food. Then you make your dog search for it. I usually ask for a sit at the edge of a square and then I give him the command "Search". When your dog doesn't know the command yet, you can throw a piece of food into the square so he would go and look for it. He/she will soon recognize that she'll only find food on the area you've stepped on. Dogs can easily differ areas with steps on from areas without. They smell the injuries on the earth. Do this serveral times, until you hear that your dog is really sniffing a lot. Another important thing is to take your dog out of these squares gently before he ate all the food, because you want him to be very curious on the search. If he knows that there would have been more, you create more interest for the next one.
After some of these squares, when you feel that your dog is really using his nose, so if he is not lifting his head up during the time you make him search for food, you can start to step out of the squares. First really put one foot after the other, heal stricly after toe. Put one piece of food in every step you take. First tracks can really only mean one square and five steps and another square for instance. Remember to drop more food at the end and make a big step out so your not distracting your dog at the end. Pull him out gently before he ate everything. Keep asking for more if your dog is successful, but take small steps. When he followes the heal after toe tracks well, you can start to put your feet further away from another. But remember to raise criteria slowly, so your dog can be successful and excited about tracking! I always use the squares at the beginning to make to dog focused on the track. They are a bit smaller now though. Just my two feet next to another. And I mark the beginning of each track with a special stack, to also give my dog a visual sign.
After a lot of small tracks you can start to reduce the food, maybe only every 5, 8. and 12th step for instance.
Have fun! (I hope this was helpful)
My dog loves to do tracking, this method is really great, and it works strictly in a positive way.