Here is a useful address to obtain information from St. Pierre & Miquelon.
Services des Archives de la collectivité territoriale
Place de l"Eglise, B.P. 4200
97500 Saint-Pierre, France
I am looking also for an Elizabeth Slaney. The one I'm looking for was married to William Breack. She was from St. Lawrence I was told, however she died in St. Pierre. I have a copy of her death inscription. I'm not sure if it's the same Elizabeth Slaney that you are looking for. This Elizabeth Slaney had several children where one of the son's moved to Codroy Valley, married and moved to Corner Brook, NFLD. I am part of this family.