There is a photo of the Pope having his forehead anointed by an Indian woman, but she was a Catholic, not a Hindu priestess! She was giving the Pope a traditional Indian form of greeting known as Aarti, which has no more religious significance than a handshake does in Western culture.
A letter dated November 22, 1994, from the Pontifical Council for Social Communications explains the custom and its role in Indian society:
Indian Catholics . . . use Aarti when a child returns home after receiving First Holy Communion and when a newly married couple are received by their respective families. Nowadays, Aarti is often performed to greet the principal celebrant at an important liturgical event, as it was on the occasion shown in the photograph. On such occasions, Aarti is usually offered by a Catholic married lady and certainly not by a “priestess of Shiva” as has been alleged.
The letter, by Archbishop John P. Foley, went on to note: “Use of the Aarti ceremonial by Indian Catholics is no more the worship of a heathen deity than is the decoration of a Christmas tree by American Christians a return to the pagan rituals of Northern Europe.”
Your friend in the Society of St. Pius X should check his facts before spreading such malicious gossip about the Holy Father (cf. Acts 23:1-5).