I haven't looked at your capx yet.
You could use that in JavaScript run with the browser object. You wouldn't be able to access the canvas plugin but you could still use a html canvas and return it's asURL string to load in a Sprite or some other object. Still it would still just be an image and that doesn't help with collisions.
Well looking at that draw script again, you'd need to convert it over to canvas functions, they wouldn't work as is.
In editor editing of curves isn't possible in C2, but probably in C3.