An enhanced version, with features not included in the one released by Logitech, is floating around as pt20pc.zip. It was released to the public domain, with source, by the author, Charlie Crowley, at the University of New Mexico's Computer Science Department.
One place to find it is here: http://sunsite.rediris.es/pub/msdos/editor/pt20pc.zip
And docs are also available from the same place: http://sunsite.rediris.es/pub/msdos/editor/pt20txt.zip