St-Victor d'Alfred wasn't established until 1871. The only parishes active in 1860 in Prescott were L'Orignal, Curran, and St-Eugene.
Civil registrations didn't start until 1869. Seemingly, as she was French, she would also be Catholic, but one doesn't necessarily follow the other :) I've been checking through the Drouin images (which are indexed) but I'm not finding her, even with first name only searches (Tharsile/Tarsile), nor last name only searches (Martineau, Martino). The priests usually entered women by the maiden name, but I'll check Cusson as well. Will repost if/when I find it