My local library was able to find a copy of a piano tuning
correspondence course.  I believe it was from a Wisconsin library.

I don't recall the name of the company, but it was in the bibliography
of Reblitz's Piano Tuning and Restoration book (which also has
information on tuning).  The content seemed good, once you got past
the home-made video with the little kids talking in the background.
:-)

This is an older version of the course which, of course, no longer
contains the tools, nor the interaction with the instructors.  It
will give you a good look at what's involved in tuning and regulating.
The notes include basic tuning procedure and two methods of setting a
temperament.  The company still exists and offers an updated course.
Perhaps someone in the business knows this course and can comment on
it.

I've found the books by Arthur A. Reblitz to be very helpful.
While I've got a long way to go, they have taught me how to safely
disassemble the pianos around home and church to remove those pencils
and clean the spills, dust, and such :-)

Mike Blackwell