I have converted two harpsichords to MIDI operation, the first using
under-the-key solenoids was described in MMDigest:
  http://mmd.foxtail.com/archives/Digests/200102/2001.02.22.01.html

The second was a keytop unit which I played at both an MBSI and an
AMICA convention.  After I purchased my first harpsichord from a dealer
in Toronto I kept her up-to-date with the progress of the conversion.
She was fascinated with the project and put my letters and some photos
of both harpsichords on her web site at
  http://www.claviersbaroques.com/PDWittmayer.htm

Regarding music for the harpsichord, I would not worry too much about
it.  There are tens of thousands of MIDI files available on the
Internet, both classical and popular.  Surprisingly, many sound just
fine on the harpsichord.  MIDI files arranged for guitar and for banjo
are particularly good.  After all, the classic insult that a musician
can make about the harpsichord is that it sounds like a banjo.

If you manipulate the files by lengthening every note you get sort of
a sustain which gives a strange different sort of sound.  (There is one
harpsichordist who claims that this is a more historically accurate
approach to playing than the modern approach.)

One last thing: after you download MIDI files you will probably have
to adjust them to ensure there is a minimum time gap between any two
identical successive notes.  After you have done the MIDI conversion
you can easily determine the number of milliseconds gap that is needed
for good repetition.  There are a number of MIDI programs that will
do this automatically; don't even think about doing it manually!

Good luck -- it is a worthwhile project.

Phil Dayson
Vancouver, B.C., Canada