The actual plan is much simpler, but brilliant. This is what I know of Operation Canucky Freedom.
Starting in early Autumn the US government will be sponsoring discount vacations for Canadians to visit Florida, which most of them do every year anyways. On the night of the invasion a case of LaBatts will be sent to every hotel or motel room in Florida. Simultaneously every channel in Florida will show re-runs of hockey games. Midnight all the phone and Internet connections are severed and the airports are closed.
The original plan included blocking highways out of Florida, but it was scrapped out of concern for economic repercussions, the fact that there are a lot of roads out of Florida, and realistically at the speed Canadians drive, it would be months before they got home.
While most of Canada's population is securely in Florida the actual invasion will commence. Several divisions of brownies and girl scouts, supported by a few regiments of boy scouts with sling shots will cross the border and seize all major cities.