On 21 November 1897 at Bern he was a co-consecrator of Anthony Stanislaus Kozlowski of Chicago to be a bishop for the Polish Catholic Church of America. The main consecrator was Eduard Herzog of the Swiss Christian Catholic Church; the other co-consecrator was the Theodor Weber of the Old Catholic Church of Germany. On 29 September 1907, at Utrecht, Gul was the main consecrator of Franciszek Hodur, from Scranton, Pennsylvania, for the Polish National Catholic Church (PNCC), assisted by Johannes Jacobus van Thiel, Bishop of Haarlem, and Nicholas B. P. Spit, Bishop of Deventer. On 5 October 1909 he consecrated Jan Maria Michał Kowalski, the first Minister Generalis (Minister General) of the order of the Mariavites.