Check out the EHX Effectology video series by Bill Ruppert. I don't know if there is one specifically on harpsichord, but he shows you how to get lots of different non-traditional guitar sounds from various combinations of pedals.
Here is the one with steel drums:
https://youtu.be/x6mNpmCEsOM
Here is the one with steel drums:
https://youtu.be/x6mNpmCEsOM