I think using MS Paint you have three alternatives, 1) Extreme time consumption, 2) Comprimise over what you change, 3) Shoddy results. Personally I don't like any of the options, although I think the time thing is fairly irrelevant on this challenge, because it will be time consuming whatever program you use.
I am having to do so much manually and the perspective is proving a real arse with the shapes I want to use, that said, I'm somewhat happier with my progress than I was a few hours ago. Should easily be finished before Friday now.