Wow, while since I posted here.
I've just finished adding support for adding curved paths to the editor. They are multi-segment quadratic bezier curves and you can pull the points about with the mouse. The funky little pawprint icons are meant to represent a path.
This all started because I wanted to be able to have the camera follow smooth paths during cut sequences and has taken weeks to get right. I've not fully finished the editor functionality yet and have no idea how to actually track along the curves at a constant speed in the game but I'm sure it will be solvable.