Hi, I had a look in my LATCH manuals (2007, 2009 and the current 2011 edition just to double check in case the older editions had any Renault info.) and there's no Renault section at all, most likely due to Renault's (and other French brands, like Peugeot and Citroen's) fairly lengthy absence from the U.S. car market.
Despite its connection with American Motors Corp. (AMC)/Chrysler back in the day, the Alliance is not listed in the Chrysler section of the LATCH manuals I have access to either, nor is there an AMC section. I think the nearest Renault/French branded car dealers to North America are in St. Pierre and Miquelon based on an article in the current issue of Car and Driver about a car journalist's failed attempt to drive a 1980s era Citroen from the U.S. "back to France" in St. Pierre and Miquelon (the car died en route and was refused passage as a towed vehicle on the final ferry ride portion of the journey, lol), but I may be wrong on that since technically the author was hoping to drive the car to French territory and not just to Canada.
If there are actual Renault dealers in your region of Canada, inquiring there might yield you an answer. Otherwise, in absence of any solid lead on an official Renault tether anchor retrofit, the EZ-On suggestion above is a good one to pursue IMHO if possible.