Mac Tac? I assume that this is basicly contact paper? If so, you may not enjoy this. Some one else may have a better idea that will make me slap my forehead and say something stupid like "DOH".
I have removed contact paper from shelving and other areas by saturating it with Lacquer Thinner. This is nasty smelling stuff and is rather toxic, so make sure you have ventilation. Holding a rag saturated with this stuff against the surface will loosen the adhesive and allow you to remove it, but it will leave most of the adhesive behind. It may take a few minutes to penetrate the surface. Clean the rest of the adhesive off with more thinner and successive rags. You'll need to repaint though, lacquer thinner will also take the paint off your wall! I'd suggest that you try this in a small area first to see if it will work without distroying your walls.