I found the following post when looking for an answer of how to toggle CFM from another extension. In the post you say " I have custom code that can do this. It creates a prefix *22 that you can dial in front of a valid system extension to toggle the Follow Me." and the guy you are helping acknowledges following your steps and having it “work perfectly”. Those steps are listed. Maybe private message?
The admin of that forum saw fit to purge all my thousands of posts, and I don’t have the dialplan any more. Perhaps a Samaritan here has a record of it.