It was first published in its entirety by Felice Tocco, "Il processo dei guglielmiti",
Rendiconti della R. Accademia dei Lincei. Atti della classe di scienze morali Series 5, vol. VIII (Rome, 1899), pp. 309-342, 351-384, 407-432, 437-469.
Fortunately this volume has been scanned, accessible at Internet Archive and via Google Books -
http://www.archive.org/details/rendicon ... 11filogoog
However, Tocco did not translate it.
The new edition of reference is Marina Benedetti, ed.,
Milano 1300: I processi inquisitoriali contro le devote e i devoti di santa Guglielma (Milano, Libri Scheiwiller, 1999). This is accompanied by an Italian translation.
Benedetti is the text I quoted in this thread -
viewtopic.php?f=14&t=581&start=10#p8395
Giovanni Puricelli never published the manuscript. He left a manuscript summary of it, with his own observations, to the Ambrosiana in 1676. This summary was itself summarized by Ludovico Muratori in his
Antiquitates italicae medii aevii (6 vols., 1738-1742). A 1778 edition of this is available here -
http://www.archive.org/details/antiquitatesital12mura
- columns 451-455.