Hey Julien, I did the drive from Whistler back to TO a year ago - I did 5 SOLID days of driving. 14 hours Whistler to Calgary first day, 12 or so to Brandon Manitoba second, 10 or so to Thunder Bay, then 7 or so to Sault St Marie and 7 to Toronto. I think you are dreaming with 3 days, let alone 4.
I took the TransCanada the whole way as well - there is a route across from Ottawa to towards the Sault that you should take - going into the states is silly from Montreal as you have to go around Southern Ontario and it would take more time, unless you have some sort of mission there.
Highway 17 through Ontario is a way nicer drive than 11, but both of them meet up in Thunder Bay anyhow. From there, its the same highway all the way to Calgary, then you have some options again as you go through the rockies. Most should be ok this time of year.
'The money's in the medicine, not the cure!' Harvey