the repaint should not be a problem But it is not possable to add or alter parts of any air craft with out having the orignal source code. So you would have to make a whole new aircraft from scratch.
There is a good chance you can find a repaint for the aircraft on the net there are a ton of them out there look here in Simviation and 8)

You could down load one of the paint programs and try to repaint the plane your self. I have never tried this but have thought about it. Try looking in the repaint section you might find some idears there on which program is the best. 8)