I managed to modify and "compile" the first level a little.
I replaced the 2 first screens with some random image (I actually tried to swap the background of the 2 first screens, but I can random stuff instead).
The game can read the cam files without crash.
Yet the cam converter crashes when trying to process them. :P
Paul, can you post more information about how are the cam files working? Especially the header.
If you can post the source code of the cam converter (If it's C or C++) that would be great.