From TorahWeb:
Regarding the upcoming papal funeral TorahWeb's Rabbinic Board (Rabbi Michael Rosensweig, Rabbi Hershel Schachter, Rabbi Mayer Twersky, Rabbi Mordechai Willig) would like to inform the public of the followingSee Nefesh Ha-Rav, p. 230. I'll add that I reminded people about this regarding Princess Diana's and President Reagan's funerals.
In 1963 Rav Soloveitchik zt"l reacted to reports of Jews watching television coverage of President John F. Kennedy's funeral service. At that time the Rov was distressed and stated that, according to Halachah, it is forbidden for a Jew to watch such a religious funeral service.