If your using standard images and changing certain things of them then i would suggest flash, it wouldnt be to hard, but changing the images(text/background)of the stickers and changing there color i wouldnt be to confident about. But I am not the greatest flash programmer.
Maybe you could have a lil side bar with tiny thumbnails on the side(with different instance names to the main screen one) once u click it, it removes the current MovieClip from the stage and imports the other one onto the stage with the same instance name, but different linkage names. then you could just have RGB toggle buttons to change the colors etc.
Im not sure whether that would work, but i currently have a project like that in my multimedia class similar to that.(random falling objects that i can change between and change colors)
some one tell me whether its doable coz i dont want to waiste my time, though i think i have it working pretty well in my head.