He has written a short tutorial on how he did it last year and how you can as well, complete with lots of links. For example he discussed
- setting objectives
- proficiency scoring - which he based on formative tests.
- summative tests
- re-takes of summative tests which are only given on the portion of the objective that was not proficient and were not given unless students could show proficiency in a topic
- what goes into the gradebook (hint - only summative which he explains)