Keep in mind that these rules are a work in progress, an attempt to balance out a feature I’ve wanted to implement for a long time. We’ll see how this works out.
In order to train a feat, you must meet all prerequisites for learning the feat naturally. First find a partner who has the feat and is willing to teach you. Training will take both the student and teacher a number of hours equal to 8 + 4 for every prerequisite of the feat. In other words, to teach Weapon Focus (Longsword) it would take a total of 12 hours; 8 hours plus an additional four, as Weapon Focus (Longsword) requires that you be proficient with a longsword. You cannot train for more than eight hours a day.
Training feats costs both the teacher and the student XP. The teacher must pay an amount equal to his or her level multiplied by 150, and the student must pay an amount equal to his or her level multiplied by 400. Experience is paid at the beginning of the training. Upon completion of the training, the student permanently gains the feat.