i taught a DAT course this past fall for kaplan, and i'm currently teaching an MCAT course. you need a 90th percentile or above in the test you are teaching. there is a 4-5 week training period, then you are on your own to teach classes. pay is 20/hr for class time and 7/hr for out of class preparing of lessons, which you do on your own time and is self reported.
its a pretty good deal. the time commitment is whatever you want it to be. they give you a schedule of available classes and you pick which one(s) you want to teach, and that's that. you can do as much or as little as you want. i'm teaching in addition to my full-time job, and i've been doing it for about 6 months now and its starting to get old. after my MCAT class ends in March, I won't be taking on any more classes because i want to enjoy at least SOME of my year off between college and dschool 🙂