Hi Jake, thanks for this useful tutorial, it also helps take away a large chunk of anxiety and reservation people still harbour towards the open source boards.
The re-calibration can be done the same way on the home brew solutions as well. I also have a test sketch people can use if they put together an own solution:https://github.com/Protonerd/DIYino/blob/master/DIYino_Testsketch_Pro.ino
My DIYino boards already come pre-calibrated, this is a part of the testing I perform to ensure that all boards I send out are perfectly working. The test sketch I linked in has an excellent test coverage of the other modules as well, like the sound chip, the LED drivers etc.