This is a script that creates camera according to perspective lines on your image. It is sort of a beta version and has no error handling yet, so be warned:).
1 - get an image for which you want a camera being created.
2 - run the script (it is ordinary maxscript).
3 - press first button in UI and select the image
4 - an image plane and helper curve will be created
5 - modify helper curve (subcurves) so that they follow perspective lines, the vanishing points with three pairs of subcurves